Meanwhile, authorities tried to confirm that a body found in a lakeside grave was that of the San Diego County student who has been missing for nearly a week.
District attorney's spokesman Paul Levikow did not immediately specify the charges planned against John Albert Gardner III, saying the complaint was still being written. The counts will be disclosed at an arraignment later in the day, he said.
The 30-year-old Lake Elsinore man was arrested Sunday on suspicion of murder and rape.
Police said a spray-painted message found on the garage of the suspect's mother read, "Chelseas blood is on you. Move out." Police did not know who painted it.
Gardner lived at the Rancho Bernardo home in 2000 when he molested a 13-year-old neighbor. The home is down the street from an elementary school and near the park where King was last seen Thursday wearing running clothes.
A piece of paper taped to the front door told visitors to leave.
As prosecutors prepared their case against Gardner, the county medical examiner's office worked to confirm King's body had been pulled Tuesday from a shallow grave on the south shore of Lake Hodges.
An investigator was meeting with King's parents at their Poway home, said Lenore Aldridge, a medical investigator.
It was not clear if fingerprints, dental records or other methods of identification were being used.
County Sheriff William Gore said the body was likely King.
Thousands of people joined the search after the teen failed to return from a run near the lake on Thursday.
Mourners held a candlelight vigil Tuesday night for the popular straight-A student at Poway High School.
"What bothers me most is the kids don't feel safe anymore," Traci Barkerball, King's teacher for three years, said between hugs of grieving students. "Their sense of security has been taken away from them."
Brent King, Chelsea's father, thanked supporters on the lawn of St. Michael's Church in Poway, northeast of San Diego. Some people in the audience fought to control their sobs as he spoke.
"One of the nicknames that I've always called my daughter is my Angel. She's my angel forever," he said. "I want to thank you. Chelsea wants to thank you."
Someone shouted, "We love you," and Brent King replied, "We love all of you."
Gardner was arrested after police said a piece of physical evidence tied him to King. No further details were provided.
Gardner pleaded guilty in May 2000 to molesting the 13-year-old female neighbor and served five years of a six-year prison term. Prosecutors said he lured the victim to his home with an offer to watch "Patch Adams," a 1998 movie starring Robin Williams.
The girl was beaten before escaping and running to a neighbor. Gardner "never expressed one scintilla of remorse for his attack upon the victim" despite overwhelming evidence, prosecutors wrote in a sentencing memo.
He had faced a maximum of nearly 11 years in prison under terms of a plea agreement, but prosecutors urged six years.
Dr. Matthew Carroll, a psychiatrist who interviewed Gardner, had urged "the maximum sentence allowed by law." He said in court documents that Gardner was a "continued danger to underage girls in the community" and an "extremely poor candidate" for treatment."
Dr. Mark Kalish, who shares an office with Carroll, said his colleague was saddened and angered by the news about Gardner, feeling his advice was ignored.
"He didn't want there to be any ambiguity or doubt about his assessment. He laid it out there and he was essentially ignored by the district attorney's office," Kalish said. "How much bigger a red flag could Dr. Carroll have raised?"
Kalish said Carroll was referring calls to him because his colleague, who does work for the county, did not want to discuss the case publicly.
Carroll, a court-appointed psychiatrist, reached his conclusion because Gardner took no responsibility despite evidence, described in the prosecution sentencing memorandum, of the girl's frantic escape.
"How are you going to treat someone who says you got the wrong guy?" Kalish said. "This girl ran out of (his) house with her pants down. Come on!"
The district attorney's office has declined to comment on the 2000 case.
Gardner was on parole for three years, until September 2008, state records show.
San Diego police said Gardner also was linked to an assault on a 22-year-old Colorado woman who managed to fend off her attacker on Dec. 27 in Rancho Bernardo Community Park on the northern edge of San Diego, where King's 1994 BMW was found with her belongings inside.
San Diego police Capt. Jim Collins declined to describe the evidence connecting Gardner to the December assault but said a swab taken from the victim's elbow did not match Gardner's DNA.
