Columbine's Legacy: More Than 50 School Attacks, Plots

A months-long investigation by ABC News has identified at least 17 attacks and another 36 alleged plots or serious threats against schools since the assault on Columbine High School that can be tied to the 1999 massacre.

AUGUST 19, 2014: SOUTH PASADENA, CALIF. A 16-year-old and 17-year-old were arrested for allegedly plotting what police described as a "viable" school "massacre" at South Pasadena High School. South Pasadena Police Chief Art Miller told ABC News the two suspects spent a lot of time playing a video game called "Super Columbine Massacre RPG [Role Playing Game]," studying it to copy the Columbine shooters' tactics. The teens have denied the charges against them, and they have been reportedly placed under house arrest as the case continues.

JUNE 13, 2014: CHURCH HILL, TENN. Two teenagers were arrested for allegedly planning to open fire inside Volunteer High School and kill as many people as possible. Police allege that journals by one of the teenagers revealed an obsession with Columbine and serial murders. The teenagers are awaiting a judge's decision on whether their case will be prosecuted in juvenile court. They have not yet entered pleas.

JUNE 5, 2014: SEATTLE. A 26-year-old man carrying more than 50 rounds opened fire at Seattle Pacific University, killing one and injuring two others. In his journal, obtained by ABC News and its affiliate KOMO-TV in Seattle, the alleged shooter called Columbine shooter Eric Harris one of his "idols," writing that since the massacre in 1999, "I've been thinking about [such attacks] a lot." He wrote: "I can't believe I'm finally doing this! So exciting I'm jumpy." In court, he pleaded not guilty and is expected to mount an insanity defense.

MAY 1, 2014: WASECA, MINN. A 17-year-old student at Waseca Junior/Senior High School was arrested for allegedly planning to kill his family and then bomb his school on the anniversary of Columbine. In a 180-page journal found in his home, the 17-year-old detailed his plan and described his obsession with the Columbine killers and other mass shooters. In his interrogations with police, copies of which were obtained by ABC News, the suspect allegedly said he planned the attack because it would be "an opportunity to get out of here," because it would be "fun," and "to follow my idol ... Eric Harris." He also said he had been hiding the fact that he is "really mentally ill." At the time, his father told reporters he believes his son would not have actually carried out an attack. The 17-year-old faces charges of possessing explosive devices, after a judge threw out some of the most serious charges against him. Prosecutors are trying to get those charges reinstated. A lawyer for the 17-year-old declined to comment for this story.

APRIL 9, 2014: MURRYSVILLE, PA. A 16-year-old boy wielding two "kitchen-type" knives began stabbing fellow students at Franklin Regional High School, injuring 22 people. The boy initially planned his attack for April 20 - the anniversary of the Columbine attack - but moved it to April 9, Columbine shooter Eric Harris' birthday, a psychologist for the boy's defense testified in a pre-trial hearing. "He got online and did extensive research on Columbine," Dr. Bruce Chambers told the presiding judge on Sept. 26, as recounted to ABC News by defense attorney Patrick Thomassey.The boy felt alone and like he didn't fit in, and he told doctors he believed the Columbine shooters were working through him during his attack - an attack he expected would end with his death, Thomassey confirmed. The boy is awaiting trial, and a judge said he should receive treatment in the meantime. He initially pleaded not guilty to charges against him.

MARCH 4, 2014: DANBURY, CONN. An 18-year-old woman and 19-year-old man were arrested for allegedly planning a shooting massacre at Danbury High School. According to documents obtained by ABC News, they allegedly searched YouTube for Columbine-related videos, and in a notebook the woman wrote: "I can't even stop thinking about Columbine and Eric [Harris] and Dylan [Klebold]. I mean like they're my heroes ... I never knew them but I miss them. I went through everything they went through and I wanna follow in their footsteps." The woman first learned about Columbine in school, the woman's mother told police. The case is pending in court.

DEC. 17, 2013: TUMWATER, WASH. Tumwater Police Department arrested a 14-year-old student at Black Hills High School after he allegedly talked about "shooting up" his school, according to police records. Police "learned that [he] has been obsessing about the shootings at Columbine and idolized the shooters in that mass shooting incident," according to police reports obtained by ABC News. The boy later told police a 9mm handgun and 12-gauge shotgun were in his bedroom and admitted to researching Columbine online. He allegedly told police he found the Columbine shooting "interesting" but would never follow through on such an attack, according to police reports. He pleaded not guilty to the charges against him.

DEC. 13, 2013: ARAPAHOE, COLO. An 18-year-old student armed with a shotgun, multiple rounds of ammunition, a machete and two Molotov cocktails opened fire inside Arapahoe High School. Two students were injured. The shooter was allegedly planning to target a member of the faculty and then harm others, according to police. A source told ABC News the shooter was inspired by Columbine. He reportedly pleaded not guilty to the charges against him.

OCT. 21, 2013: SPARKS, NEV. A 12-year-old student opened fire at Sparks Middle School, killing a teacher, injuring two students and then killing himself, according to authorities and a press release by the Sparks Police Department. In the months before the attack, the boy looked up the video game "Super Columbine Massacre RPG" and researched videos, web sites, articles and images related to Columbine, according to police. In addition, authorities found pictures of the Columbine shooters on the boy's cell phone, police said. The boy had been teased at school and exhibited signs of depression, according to police records.

MAY 24, 2013: ALBANY, ORE. A 17-year-old junior at West Albany High School was arrested for allegedly plotting a bomb attack on his school. When police searched the boy's bedroom, they found a hidden compartment containing two pipe bombs, two Molotov cocktails two "Drano bombs," and journals detailing plans to commit "mass murder" at the school, according to police documents filed in the case. In his journals, the boy also compared himself to the Columbine shooters, and he collected information about the weapons and gear "Eric and Dylan" used in their attack, according to the documents obtained by ABC News. The case became a juvenile matter, with all charges related to trying to hurt or kill anyone being dismissed, according to his lawyer. He was found to have illegally used weapons and manufactured destructive devices, and he was committed to the Oregon Youth Authority until his 25th birthday or sooner if authorities see fit. "My client was interested in the Columbine killers and the shooting. However, my client never had a firearm, never had any access to a firearm and never had any plans to shoot anyone," the lawyer told ABC News.

DEC. 14, 2012: NEWTOWN, CONN. The 20-year-old who killed 20 children and six others at Sandy Hook Elementary School had "an obsession with mass murders, in particular the April 1999 shootings at Columbine," according to the state of Connecticut's final report on the massacre. On his computer, authorities found "Several video clips pertaining to Eric Harris and Dylan Klebold," and "hundreds of documents, images, [and] videos pertaining to the Columbine H.S. massacre including what appears to be a complete copy of the investigation," according to an appendix to the state's report. Like the Columbine shooters, he committed suicide.

AUG. 27, 2012: WHITE MARSH, MD. A 15-year-old student carrying a double-barrel shotgun opened fire in Perry Hall High School's cafeteria, injuring one student. The morning of the attack, he posted on Facebook: "First day of school, and the last day of my life." He allegedly told police he had few friends and hated the world and "his plan was to kill several people then turn the gun on himself." "He used the incident at Columbine High School as an example," according to police records. In videotaped interviews with police obtained by ABC News, he said he "thought about Columbine a little bit," but said he was unlike the shooters in that massacre because he wasn't bullied. He pleaded guilty to attempted murder and was sentenced to 35 years in prison.

JAN. 25, 2012: ROY, UTAH. Two students at Roy High School - ages 16 and 18 - were arrested for allegedly planning to set off bombs inside their school. They contemplated stealing a plane from a local airport to escape after the attack, and they spent "thousands" of hours studying and practicing how to fly small planes, according to police. The 16-year-old allegedly told police, "Columbine has always been a fascination of mine," and he told them he was "offended that he was compared to the Columbine killers" because they "only completed one percent of their plan and he was much more intelligent [than] that," according to police records obtained by ABC News. But the 16-year-old, now older, told ABC News recently the police records got it all wrong: "I wasn't offended by being compared to Columbine for that reason, I was offended because I wasn't going to actually blow up the school. There's a reason they never found bombs, explosive components, or anything." And at the time, he told police the plan was "mostly fun" and he would never kill anyone. He ultimately pleaded guilty to owning a weapon of mass destruction and spent nine months at a juvenile treatment facility. The 18-year-old pleaded no contest to criminal mischief and spent more than a month behind bars.

AUG. 17, 2011: TAMPA. A 17-year-old who had been expelled from school was arrested for allegedly plotting a bomb attack on Freedom High School. In his home, police found knives, gunpowder, tubes, fusing devices, timers and other bomb-making materials. They also found a journal laying out his plan and a calendar with the words "The event!" written on April 20, 2012 - the anniversary of the Columbine attack. And in homemade videos obtained by ABC News, he dubbed himself "the Freedom High School shooter" and said he would "beat" the Columbine killers and others. He ultimately pleaded no contest to two weapons-related charges against him and was sentenced to 15 years in prison, after begging the judge for leniency. Before his sentencing, he expressed remorse and asked for an opportunity to "do right." Though he "obviously was disturbed," a defense expert determined at the time that nothing in the boy's possession could have actually been turned into a working bomb, a lawyer who represented the boy told ABC News. Florida law "covers an attempt" to do something violent, and that's what got him, the attorney said.

FEB. 23, 2010: LITTLETON, COLO. A 32-year-old man armed with a rifle opened fire in Deer Creek Middle School, located on Columbine Drive just a few miles from Columbine High School. Two people were wounded. Prosecutors told ABC News the shooter mentioned Columbine in his rambling journals, writing in one entry: "Where I come from they, or I should say, respect life 100%, but what do I do when I'm the only one who understands that way. Are they going to listen, probably not. Like Columbine H. S. Do they ever think that some of us just ain't playing?" The shooter was found not guilty by reason of insanity and sentenced to time already served in prison - 18 months.

OCT. 20, 2009: MONROE, N.Y. A bullied 15-year-old boy was taken into custody for allegedly plotting "a Columbine-type event" against Monroe-Woodbury High School on the upcoming anniversary of the Columbine attack, according to police. In the suspect's home, police found gas-filled water bottles, a machete, a blow torch, and a black trench coat - like one worn by the Columbine shooters. Police said they believe the boy was in the "early planning stage" of the attack, had begun experimenting with explosives and was looking to obtain a high-powered gun. He later pleaded guilty to several counts of illegally owning a weapon, and he was sent to a psychiatric treatment center for 18 months, according to local media reports.

MAY 18, 2009: LAFOURCHE PARISH, LA. A 15-year-old student "filled with hate" at Larose-Cut Off Middle School walked into a classroom with a 25-caliber semi-automatic handgun in his hand, pointed the gun at a teacher, and then fired one shot into the air. While the school was being placed on lockdown, he went into a boy's bathroom and fatally shot himself in the head, police said. He was apparently planning to shoot four students at school and then take his own life. In his bedroom, police found a clipping from the local Daily Comet newspaper, which reran a USA Today article headlined: "10 years later, the real story behind Columbine."

APRIL 19, 2008: CHESTERFIELD, S.C. Police arrested an 18-year-old man after his parents reported to police that he had been sent potential bomb-making materials, and that in his bedroom they found worrisome voice recordings and writings, along with plans to bomb Chesterfield High School, according to police records. In his journal, the 18-year-old took meticulous notes about the Columbine attack and wrote, "I praise the actions of Harris and Klebold." In one of the voice recordings, obtained by ABC News, he said that if the world does not get better "Columbine III will happen." Notes and police records obtained by ABC News indicate a history of depression, anger, loneliness and other mental health issues. He ultimately pleaded guilty to federal charges in the case and was sentenced to 10 years in federal prison, where he is receiving psychiatric and psychological treatment. A lawyer who represented the 18-year-old said "it is important" to note that he was diagnosed as suffering from "major" and "untreated" mental health disorders, and that "mental illness played a defining role in the offense." Since receiving treatment, he "was courteous, respectful, and modest" with "the ability to be a productive person, and I hope that in the future someone will give him a chance to demonstrate his good qualities, rather than discarding him as some Columbine copycat."

APRIL 2008: MISHAWAKA, IND. A 16-year-old student at Penn High School was arrested for allegedly conspiring to attack his school. He had been talking online with an Ohio man about launching attacks on Sept. 11, 2008 - "an iconic date" because it's Dylan Klebold's birthday, according to court records. In an online message April 9, 2008, the 16-year-old allegedly wrote: "Eric Harris and Dylan Klebold were fighting back against society. I consider them martyrs." In a notebook, the 16-year-old wrote that his school "would not be prepared for a Columbine" and he wants to "break the current shooting record" so he can "get instant recognition," according to police records obtained by ABC News. He later allegedly told police he was just kidding about these specifics threats, but said he does have thoughts about going through with such actions. He later pleaded guilty to charges in the case and was sent to juvenile detention.

FEB. 14, 2008: DEKALB, ILL. A former graduate student at Northern Illinois University walked into an auditorium at the school carrying a shotgun and three handguns, and began shooting. Five people were killed and at least 16 others wounded before he committed suicide. The 27-year-old shooter had "examined the methods" of the Columbine killers and other shooters, and he was "fascinated" by Columbine and other incidents of violence and murder, according to a comprehensive police report on the case.

OCT. 11, 2007: PLYMOUTH MEETING, PA. 14-year-old Dillon Cossey was arrested for allegedly discussing a plot to attack Plymouth Whitemarsh High School. Police found a rifle, a stockpile of airsoft guns, gunpowder, and a copy of "The Anarchist Cookbook," which lays out how to build homemade bombs. Cossey told ABC News he first heard of Columbine about six months before his arrest, when he saw a commercial for a documentary about the shooting on TV. That sparked "a simple interest," and when he would search Google for information about the attack "the first videos that popped up were tributes proclaiming the [shooters] to be heroes," Cossey said, adding that he developed "a kind of kinship" with the shooters. But he told ABC News all he did was talk about hurting people at the school who relentlessly bullied him - "there never was a plan or a timeline or any intention to carry out an actual attack." He told ABC News that five years of court-ordered therapy and counseling helped pull him from his "dark place."

JULY 2007: SUFFOLK COUNTY, N.Y. A teenager was arrested for allegedly making "explicit threats" against students and faculty at his high school. He was allegedly planning to launch an attack on the following year's anniversary of the Columbine attacks. The plan was uncovered when a girl found a journal detailing the plot in a McDonald's parking lot and contacted authorities, according to police. Because he was a minor, the case against them is still sealed. But four years after his arrest, he pleaded guilty to planning a second attack on his school, and he was sentenced to as many as nine years in state prison. An attorney who represented him in the more recent case told ABC News it was all "pretty much just talk."

JUNE 2007: PASO ROBLES, CALIF. Police arrested a 17-year-old after he allegedly threatened in an online chat room to kill dozens of people at a local school. No guns were found, but Paso Robles Police Chief Robert Burton told ABC News the boy praised the Columbine shooters in the online discussions, saying he wanted to kill more people than they did. ABC News was unable to determine the disposition of the case, and police said they were unable to release any information on a juvenile case.

MAY 2007: BALTIMORE COUNTY, MD. A 16-year-old from the Baltimore area was taken into police custody after talking with someone online about "going to shoot people" at an upcoming prom, according to a prosecutor in the case. On the boy's computer, authorities found about 700 photographs and other documents, including a "considerable volume regarding Eric Harris and Dylan Klebold," the prosecutor said during a later court hearing in another case against the defendant. Authorities also found surveillance videos from the Columbine attack on the boy's computer. During the hearing, a defense attorney said the boy was suffering from mental illness, including depression, and was willing to receive treatment. A recording of the court hearing was obtained by ABC News. The boy received in-patient treatment for at least a year.

APRIL 16, 2007: BLACKSBURG, VA. A Virginia Tech student opened fire on campus, killing 32 people and then himself. Before the massacre, he sent rambling videos and writings to the media in which he referenced the Columbine shooters by their first names. In addition, a subsequent investigation by the state of Virginia found that as early as eighth grade - shortly after Columbine - he would express "suicidal and homicidal ideations" and write about the Colorado massacre. In one instance, he wrote a paper in English class that said he wanted to repeat the Columbine attack, according to the state's report.

APRIL 10, 2007: GRESHAM, ORE. A 15-year-old was arrested after firing two shots into classrooms at Springwater Trail High School. Two students suffered minor injuries. In his backpack, police found a spiral notebook -- one page was titled "Hit-List" with four names on it. He later told police he got the idea to shoot at his school after watching a documentary about Columbine on TV days earlier, and he told them he didn't really want to hurt anyone, he just wanted to scare them. He also said he was "psychotic" and suffering from mental health issues, according to recordings of the interviews obtained by ABC News. He pleaded guilty to assault and unlawful use of a weapon and was sentenced to nearly six years at a juvenile detention facility.

FEB 13, 2007: NEWINGTON, CONN. A 16-year-old student at Newington High School who was picked on and struggling academically was arrested for allegedly plotting to shoot and possibly bomb people he didn't like at his school. In interviews with police after his arrest, he said he was "obsessed" with the Columbine massacre and understood why the "Columbine people" felt the way they did, according to police records obtained by ABC News. In the boy's bedroom, police found two rifles and a shotgun, and a folder with pictures of the Columbine shooters on the front and a "TARGETS" list inside. In a journal found by police, the boy made several references to Eric Harris and Dylan Klebold, saying he will kill more than 13 - the number killed at Columbine, police records say. He also told police he was inclined to follow through on the attack at the time he planned it, but he had since decided against carrying it out because he was beginning to feel better about things. He pleaded guilty to making threats and building bombs, and he was sentenced to three years in prison and then five years' probation, according to the attorney who represented him. The attorney told ABC News he thinks his client "was misunderstood" at school and didn't have "the wherewithal" to actually carry out an attack. "I think he was just venting," the attorney said.

SEPT. 14, 2006: GREEN BAY, WIS. At least two students at Green Bay East High School were arrested for allegedly plotting to attack their Wisconsin school "in the near future," as police put it. Based on a tip from a fellow student, school administrators alerted police to a possible plan by the two suspects to shoot up the school and detonate explosive devices there "like Columbine," according to police. The two "hated school," "had been depressed" and "had long been fascinated over the Columbine incident and began to collect items and experiment with explosives," police said in a statement at the time. At one of the suspect's homes, police found about 20 improvised explosive devices, six jars of Napalm, nine rifles and shotguns, one handgun, camouflage clothing, gas masks, walkie-talkies, numerous pellet guns, hundreds of rounds of ammunition, evidence of target practice, and various publications on the use of firearms and combat tactics, police said. Both teens admitted to charges against them and were sentenced to at least three years in prison.

AUG. 30, 2006: HILLSBOROUGH, N.C. A 19-year-old wearing a shirt with the words "Remember Columbine" killed his father and then opened fire at Orange High School, using guns adorned with pictures of the Columbine shooters. Two students were injured. In videos and journals seized by police and obtained by ABC News, the 19-year-old spoke at length about his obsession with Columbine and admiration for those who carried it out. One of the videos captured the tour he and a relative took to Littleton, Colo., where the relative drove him to the site of the Columbine massacre and to locations where the shooters worked and lived. In other videos, he ranted about anger and love, sacrifice and sin, his alleged abusive upbringing, and his love for a girl who wouldn't "notice me." He was ultimately convicted of murder and other charges, and sentenced to life in prison.

APRIL 20, 2006: PLATTE COUNTY, MO. Two 17-year-olds were arrested for allegedly plotting an attack at the Platte County R-3 High School. According to five witnesses interviewed by police, the two teenagers told the group not to go to school on April 20 because they had made plans for a "Columbine-type" incident involving explosives, police said. One of the boys said they were going to carry out the attack because there had not been one in a while and to mark the anniversary of the Columbine massacre, the witnesses told police, according to records obtained by ABC News. According to an attorney who was involved in the case, both boys pleaded guilty to charges of making terroristic threats and spent days in a county jail. The attorney called the case a "total overreaction" by authorities, saying they never found "any evidence" of an active plot - "not even a hint of anything ever going to happen."

APRIL 20, 2006: RIVERTON, KAN. Five teenagers were arrested after a message was posted online threatening an attack against Riverton High School on the seventh anniversary of Columbine. Officials from the Cherokee County Sheriff's Office told ABC News they discovered guns, knives and ammunition in the bedroom of one of the suspects. One of the teenagers was acquitted of the charges against him. The others reportedly pleaded guilty to disorderly conduct-type offenses and were sentenced to probation for one school year.

APRIL 4-5, 2006: WINSLOW TOWNSHIP, N.J. A teenager was arrested for allegedly leading a plot "to shoot numerous individuals in the Winslow Township High School cafeteria during a lunch period" around the anniversary of the Columbine attacks, authorities confirmed to ABC News. The teenager was ultimately sentenced to six years in prison.

MARCH 23, 2005: AMHERST, N.Y. A 15-year-old high school student was arrested for allegedly plotting to blow up his school. He had put together plans and items that could be used to build bombs, and he had an extensive collection of documents about Columbine, police told ABC News. ABC News was not able to determine the disposition of the case.

MARCH 14, 2006: RENO, NEV. A 14-year-old student carrying a handgun opened fire outside the cafeteria in Pine Middle School. Though he had no targets in mind, one student was shot and survived, and another student suffered minor injuries. In the week before the attack, while contemplating it, he researched Columbine and other school shootings online, and read copies of diaries and journals left behind by Eric Harris and Dylan Klebold, the Reno Police Department told ABC News. In interviews with police after his arrest, the 14-year-old said of Columbine: "It kind of inspired me. If they could do it, I thought I could do it." The boy was reportedly sentenced to 200 hours of community service and house arrest until he completed it.

FEB 10, 2005: SPRING BRANCH, TEXAS. Police arrested a 16-year-old boy for allegedly plotting to detonate a bomb at his former high school. According to Prosecutor Brandon Dakroub of Williamson County, a search of the boy's home turned up six carbon-dioxide canisters used in pellet guns and instructions on how to turn them into an explosive device. A hand-drawn map of the school, found by police and obtained by ABC News, included a hit-list and the phrase "Remember 4:20," an apparent reference to Columbine.He pleaded guilty to amisdemeanor and was ordered to residential treatment.

SEPT 17, 2004: MARSHFIELD, MASS. Two students who were apparently picked on in school were arrested for allegedly plotting an attack on Marshfield High School sometime around the sixth anniversary of Columbine. They had visited websites about Columbine and collected material about building bombs, police confirmed to ABC News. In addition, one of the students wore a t-shirt to a school dance that featured the date April 20, 1999, and described the Columbine shooters as "heroes" in German, police said. Both boys spent several months behind bars.

SEPTEMBER 2004: CLINTON TOWNSHIP, MICH. A student at Chippewa Valley High School was arrested for allegedly planning to attack his school. At his home, police found a rifle, several high-capacity magazines and Nazi-related materials. In an online discussion, he allegedly told a girl that he was about to cause "mass murder" with a plan akin to Columbine, police confirmed to ABC News. He allegedly indicated that on the day of the attack he would be saying "peekaboo under tables" - an apparent reference to the Columbine shooters who said "peekaboo" to students hiding beneath tables before shooting them. The student was convicted of threatening an act of terrorism and other charges, and he spent more than four years behind bars, according to local media reports.

FEB. 9, 2004: EAST GREENBUSH, N.Y. A 16-year-old opened fire while walking into Columbia High School. One person was wounded. Before his attack, the shooter had watched the documentary "Bowling for Columbine," and he made references to the film in a rambling note he left in his home, police confirmed to ABC News. He pleaded guilty to attempted murder and another charge, and he was sentenced to 20 years behind bars.

JANUARY 2004: DUTCHTOWN, LA. A 17-year-old student and a 19-year-old student at Dutchtown High School were arrested for allegedly planning an attack on their school. Drawings seized by police in the case depict violent scenes with the phrases "Hellsville Welcomes You" and "Klebold Ln." In addition, the two students had allegedly written "Trenchcoat Mafia" on their student ID cards. ABC News was unable to determine the disposition of this case.

SEPT. 18, 2003: LOVEJOY, GA. A 14-year-old boy was arrested after fellow students reported hearing him talk about opening fire inside Lovejoy High School sometime before October 31, 2003. According to two of the students who tipped off officials, the boy said he "wanted to do a Columbine kind of incident" and "would make Lovejoy into another Columbine," as police put it. In the boy's backpack, police found a note about suicide, saying he hated school and hated living in this world. The boy's father said there was one pistol in the home, according to police records obtained by ABC News. Efforts to determine the disposition of the case were unsuccessful.

MARCH 21, 2003: LOS ANGELES COUNTY, CALIF. Police arrested two teenage students for allegedly plotting a bomb attack on Lawndale High School to mark the Columbine anniversary. A lawyer for one of the students insisted her client never intended to carry out the attack and was "drowning in pain" and powerlessness after being bullied by classmates, according to the L.A. Times at the time.

MARCH 11, 2003: GILBERT, ARIZ. A15-year-oldstudent at Gilbert High School was arrested for trying to recruit four others into a plan to kill fellow students using handguns, rifles and multiple explosive devices. She had discussed the movie "Bowling for Columbine" with her boyfriend and told police she looked up an article about the Columbine attack "to find out about it because she did not know anything about it," according to police records. In a note to another suspect, obtained by ABC News, the 15-year-old wrote: "[Y]ou have to be willing to shoot people, people you know, so tell me now if you want out ... Can you see the headlines? 'School Dies!' 'dozens killed' 'blood everywhere.' Weeeee!" She spent a month behind bars and was sent to treatment, according to reports at the time. An attorney had argued she never had any real intent or ability to pull off the plan she was accused of orchestrating.

NOV. 26, 2001: NEW BEDFORD, MASS. Police arrested a 17-year-old and two younger students at New Bedford High School for allegedly plotting an attack on the school that they wanted to be bigger than Columbine, according to police. Earlier, authorities began investigating "rumors" that an attack was being planned by the group, and authorities ended up finding at least excerpts of "The Anarchist Cookbook" and materials that could be used for an explosive device, but no device itself, police told ABC News. The 17-year-old pleaded guilty to conspiracy to commit assault and unlawful possession of ammunition. He was held on home confinement for a year while the case was resolved, his attorney told ABC News. The attorney said the case amounted to "talking and all fantasy" about "get[ting] rid" of peers who picked on them. The group "never made any other plans than talking about it," according to the attorney. Another attorney in the case agreed, likening it to "the witch hunts." ABC News could not determine the fate of the other two students because they were so young at the time.

MARCH 7, 2001: RIVERSIDE COUNTY, CALIF. A 14-year-old freshman at Perris High School was arrested for allegedly bringing a weapon onto school grounds and making terrorist threats. Days earlier, the boy allegedly made several threatening statements that suggested he was going to commit a Columbine-type assault on the school, according to authorities at the time. Mark Lohman, who was with the Riverside County Sheriff's office at the time, confirmed to ABC News that another student reported that the 14-year-old had said, "The only difference between Columbine and Perris is that I will leave no survivors." ABC News was unable to determine the disposition of the case.

MARCH 5, 2001: SANTEE, CALIF. A troubled teen said to have gotten "picked on a lot" launched a shooting spree at Santana High School. Bryan Zuckor, 14, and 17-year-old Randy Gordon were killed, and 13 others were injured. After the attack, students said they remembered one of the boys talking about "pulling a Columbine," according to ABC News reporting at the time. In addition, the night before the shooting, the shooter told someone about the alleged plot, but the shooter then insisted he was kidding. He later pleaded guilty to charges of murder and attempted murder, and he was sentenced to 50 years to life behind bars.

FEB. 7, 2001: FT. COLLINS, COLO. Three teenage boys were arrested after four girls told police they had information about a plot to attack Preston Junior High School. The girls told police they had seen written plans for the attack, that one of the boys had access to weapons, and that the boys were talking about doing it on April 24 to "redo Columbine." In the boys' lockers, police allegedly found detailed plans, including notes saying that that they would go to "where the preps hang out," according to police records obtained by ABC News. The apparent ringleader ultimately pleaded guilty in the case and was sentenced to as many as two years in juvenile custody. In an interview with ABC News at the time, he said he wasn't serious about carrying out a Columbine-like attack, insisting, "It was just talk" and they "didn't talk about killing people." In agreements with the state, the two others in the case received probation.

FEB. 2, 2001: HOYT, KANSAS. Three students -- ages 16, 17 and 18 -- were arrested for threatening to attack Royal Valley High School. The Jackson County Sheriff's Office told ABC News the group had discussed Columbine while talking about their plans to attack the school. Police had previously been in contact with one of them over comments he allegedly made about blowing up the school and visiting a website about making bombs, according to police records. In the suspects' homes, police found bomb-making materials, maps of the school, ammunition, and a rifle, according to police. The 17-year-old was convicted of criminal use of explosives and criminal threat, and he was sentenced to 18 months in a juvenile correctional facility, according to reports at the time. A jury acquitted the other two students of the charges against them.

JAN. 31, 2001: SAN JOSE, CALIF. Police arrested a 19-year-old for allegedly plotting to plant bombs on the campus of nearby De Anza Community College. A local drugstore photo clerk notified police that someone had dropped off film showing pipe bombs with nails taped to them, pictures of a wall filled with guns, and photos showing the 19-year-old posing with weapons. A search of his home turned up a taped apology message, plans for the attack, and an arsenal of homemade explosives and illegal firearms, according to ABC News reporting at the time. On the 19-year-old's website, they found a tribute to the Columbine killers. He was later convicted of 108 counts tied to the case, and he was sentenced to 80 years in prison. He committed suicide in 2004.

FEB. 3, 2000: PALM BEACH COUNTY, FLA. A 17-year-old student was arrested by authorities for allegedly plotting to attack Royal Palm Beach High School. His attorney at the time told ABC News this case was "the closest that we got to a Columbine copycat" in Palm Beach County. His attorney confirmed that at the 17-year-old's home, police found a journal, which included this line: "I look up to people like Hitler and I grin at Eric Harris and Dylan Klebold's act of murder and suicide." He pleaded guilty to a charge of solicitation to shoot into a building, and he was sentenced to five years of probation. The attorney representing him at the time told ABC News he responded well to mental health counseling.

DEC. 6, 1999: FT. GIBSON, OLKA. A seventh grader at Fort Gibson Middle School opened fire in school with a 9mm handgun. At least four students were injured. John David Luton, the district attorney at the time, confirmed to ABC News that "several" experts testified at trial on the boy's behalf that he had been influenced by the Columbine massacre. As an example, one expert testified during a March 2000 hearing that the boy "started wondering what he would do if he were placed in the role of the [Columbine] perpetrators that were previously depicted on the TV and media," Luton confirmed. The boy was convicted on six counts of shooting with intent to kill and one count of carrying a gun onto school property, and spent more than five years behind bars, according to reports at the time.

OCT. 28, 1999: CLEVELAND. Four boys were arrested for allegedly plotting a shooting rampage at South High School to coincide with homecoming. The Cuyahoga County Prosecutor's Office confirmed to ABC News that for about two weeks, the group discussed - almost daily - their desire to do a Columbine attack, and they were seeking to recruit additional children to participate. In addition, the four boys had access to guns and had maps of the school, according to the prosecutor's office. All four ended up pleading guilty in the case, and the two apparent ringleaders were sentenced to at least a year in state custody while the other two were sentenced to at least six months in custody, according to reports at the time.

MAY 20, 1999: CONYERS, GA. A 17-year-old student opened fire at Heritage High School, injuring six. In a three-page letter found in his bedroom and obtained by ABC News, Solomon described himself as part of "the Trenchcoat Mafia." And after his arrest, he wrote that he "had just gotten the idea from the shooting at Columbine High School on April 20." He pleaded guilty but mentally ill, and he was sentenced to 40 years in prison - a sentence that was later reduced to 20 years.

MAY 12, 1999: PORT HURON, MICH. Police arrested a group of students for allegedly plotting to attack Holland Woods Middle School. One witness told police they "wanted to copy the Colorado incident," according to police records obtained by ABC News. In addition, when one of the students brought a Time magazine with Columbine on the cover to class, he told people he needed it for information, according to police. ABC News was unable to determine the disposition of the case.

ABC News' Megan Joyce, Leila Gharagozlou, Julia Noel and Lori Neuhardt contributed to this report

EDITORIAL NOTES: This ABC News investigation looked at the narrow universe of cases in the United States where (1) a school was the target or alleged target, and (2) Columbine was mentioned. There are countless school attacks and plots that were inspired by other mass shootings, including cases inspired by the Virginia Tech massacre. In addition, there are other attacks not aimed at schools - inside and outside the United States - that were inspired by Columbine. ABC News was not able to determine the disposition of all cases listed above, particularly in some cases involving juveniles.