Paul Ciancia was so determined to take lives that, after shooting a TSA officer and going up an escalator, he turned back to see the officer move and returned to finish him off, according to surveillance video reviewed by investigators.
In a news conference announcing charges against Ciancia, U.S. Attorney Andre Birotte Jr. spelled out a chilling chain of events at LAX that began when Ciancia strode into Terminal 3, pulled a Smith & Wesson .223-caliber assault rifle from his duffel bag and fired repeatedly at point-blank range at a TSA officer. The officer was checking IDs and boarding passes at the base of an escalator leading to the main screening area.
After killing that officer, Ciancia fired on at least two other uniformed TSA employees and a civilian airline passenger, who were all wounded. Airport police eventually shot him as panicked passengers cowered in stores and restaurants.
Ciancia, 23, was hit four times and remained hospitalized Saturday, but there was no word on his condition. He was shot in the mouth and the leg, authorities said.
The duffel bag contained a handwritten letter signed by Ciancia stating that he had "made the conscious decision to try to kill" multiple TSA employees and that he wanted to stir fear in them, FBI agent in charge David L. Bowdich said.
Federal prosecutors filed charges of first-degree murder and commission of violence at an international airport. The charges could qualify him for the death penalty.
The FBI was still looking into Ciancia's past, but investigators said they had not found evidence of previous crimes or any run-ins with the TSA. They said he had never applied for a job with the agency.
Authorities believe someone dropped Ciancia off at the airport. Agents were reviewing surveillance tapes to piece together the sequence of events.
"We are really going to draw a picture of who this person was, his background, his history. That will help us explain why he chose to do what he did," Bowdich said. "At this point, I don't have the answer on that."
The note found in the duffel bag suggested Ciancia was willing to kill almost any TSA officer.
"Black, white, yellow, brown, I don't discriminate," the note read, according to a paraphrase by a law enforcement official briefed on the investigation. The official spoke on the condition of anonymity because he was not authorized to speak publicly.
The screed also mentioned "fiat currency" and "NWO," possible references to the New World Order, a conspiracy theory that foresees a totalitarian one-world government.
When searched, the suspect had five 30-round magazines, and his bag contained hundreds more rounds in boxes, the law-enforcement official said.
Terminal 3, the area where the shooting happened, reopened Saturday. Passengers who had abandoned luggage to escape Friday's gunfire were allowed to return to collect their bags.
The TSA planned to review its security policies in the wake of the attack. Administrator John Pistole did not say if that would mean arming officers.
As airport operations returned to normal, a few more details trickled out about Ciancia, who by all accounts was reserved and solitary.
Former classmates barely remember him and even a recent roommate could say little about the young man who moved from New Jersey to Los Angeles less than two years ago. A former classmate at Salesianum School in Wilmington, Del., said Ciancia was incredibly quiet.
"He kept to himself and ate lunch alone a lot," David Hamilton told the Los Angeles Times. "I really don't remember any one person who was close to him .... In four years, I never heard a word out of his mouth."
On Friday, Ciancia's father called police in New Jersey, worried about his son in L.A. The young man had sent texts to his family that suggested he might be in trouble, at one point even saying goodbye.
The call came too late. Ten minutes earlier, police said, he had walked into the airport.
In the worrisome messages, the younger Ciancia did not mention suicide or hurting others, but his father had heard from a friend that his son may have had a gun, said Allen Cummings, police chief in Pennsville, a small blue-collar town near the Delaware River where Ciancia grew up.
The police chief called Los Angeles police, who sent a patrol car to Ciancia's apartment. There, two roommates said that they had seen him a day earlier and he had appeared to be fine.
But by that time, gunfire was already breaking out at the airport.
"There's nothing we could do to stop him," Cummings said.
The police chief said he learned from Ciancia's father that the young man had attended a technical school in Florida, then moved to Los Angeles in 2012 hoping to get a job as a motorcycle mechanic. He was having trouble finding work.
Ciancia graduated in December 2011 from Motorcycle Mechanics Institute in Orlando, Fla., said Tina Miller, a spokeswoman for Universal Technical Institute, the Scottsdale, Ariz., company that runs the school.
A basic motorcycle mechanic course takes about a year, she said.
On Friday, as swarms of passengers dropped to the ground or ran for their lives, the gunman seemed to ignore anyone except TSA targets.
Leon Saryan of Milwaukee had just passed through security and was looking for a place to put his shoes and belt back on when he heard gunfire. He managed to hide in a store. As he was cowering in the corner, the shooter approached.
"He looked at me and asked, 'TSA?' I shook my head no, and he continued on down toward the gate," Saryan said.
Authorities identified the dead TSA officer as Gerardo I. Hernandez, 39, the first official in the agency's 12-year history to be killed in the line of duty.
Friends remembered him as a doting father and a good neighbor who went door-to-door warning neighbors to be careful after his home was burglarized.
In brief remarks outside the couple's house, his widow, Ana Hernandez, said Saturday that her husband came to the U.S. from El Salvador at age 15.
"He took pride in his duty for the American public and for the TSA mission," she said.
Associated Press writers Alicia Chang in Los Angeles and Geoff Mulvihill in New Jersey contributed to this report.