Lt. Gen. Suwat Tumrongsiskul, head of Thailand's immigration police, said he was not present for the questioning, which was conducted by U.S. law enforcement officials. But according to what he was told of the interrogation, the 41-year-old suspect,, "said he drugged the child," according to the Thai officer.
He added that Karr said he had then had sex with the child, and that she was still alive at that point. But he said the suspect said he then realized he had "accidentally" killed her.
An autopsy said a blood screening showed no drugs or alcohol in the child's body but said she had vaginal abrasions.
Karr has not yet been formally charged, Boulder, Colo., district attorney Mary Lacy said in a news conference Thursday, adding that there is "much more work" to be done in the case. She warned the public not to "jump to conclusions," and suggested that the arrest may have been forced by other circumstances, including the need for public safety and fear that Karr might flee.
Karr will be taken within the week to Colorado, where he will face charges of first-degree murder, kidnapping and child sexual assault, Ann Hurst of the Department of Homeland Security told a news conference in Bangkok. Karr was given a mouth-swab DNA test in Bangkok, according to a law enforcement official, and will be given another DNA test when he returns to the United States, the official said.
"I was with JonBenet when she died," Karr told reporters Thursday, visibly nervous and stuttering as he spoke. "Her death was an accident."
Asked if he was innocent of the crime, Karr said: "No."
However, the suspect's ex-wife, Lara Karr, who divorced him in 2001, told KGO-TV in San Francisco that during Christmas season of 1996, when JonBenet Ramsey was strangled and beaten to death in Colorado, she and her then-husband were living in Alabama — and that she was with him the entire Christmas season.
No evidence against John Karr has been made public beyond his own admission. U.S. and Thai officials did not directly answer a question at the news conference Thursday about whether there was DNA evidence connecting him to the crime.
As Karr was escorted to his guesthouse by U.S. and Thai authorities to pick up his belongings, he told the AP: "I am so very sorry for what happened to JonBenet. It's very important for me that everyone knows that I love her very much, that her death was unintentional, that it was an accident."
Asked what happened when JonBenet died, he said: "It would take several hours to describe that. It's a very involved series of events that would involve a lot of time. It's very painful for me to talk about it."
Dressed in a baggy turquoise polo shirt and khaki pants, Karr said that JonBenet's death was "not what it seems to be," though he declined to elaborate. "In every way," he added, as authorities bundled him into a waiting vehicle, "it's not at all what it seems to be."
An investigation that seemed to go nowhere, combined with lurid details and striking videos of the girl coquettishly performing in child pageants, propelled the case into one of the highest-profile mysteries in the United States.
Some feared the case would never be solved — and as investigators failed to produce suspects, some suspicion fell on the girl's parents, John Ramsey and his wife, Patsy, who died of ovarian cancer in June.
Lin Wood, the Ramsey family's longtime attorney in Atlanta, said that Karr had sent numerous e-mails in recent months making statements about the murder to a professor at the University of Colorado at Boulder. A source described the e-mails to CBS News as "hair-raising — to see what he'd done, or contemplated doing, to children."
Karr had been in Thailand five times over the past two years, arriving most recently in Bangkok on June 6 from Penang, Malaysia, Suwat said. He was looking for a teaching job in Thailand, Thai police official Lt. Gen. Suwat Tumrongsiskul Suwat said.
Suwat told reporters that Karr insisted his crime was not first-degree murder.
"He said it was second-degree murder. He said it was unintentional," Suwat said. He said Karr told Thai interrogators that he picked up JonBenet at her school and brought her to the basement. "He said he loved this child, that he was in love her. He said she was very pretty, a pageant queen. She was the school star, she was very cute and sweet."
The Thai officer quoted the suspect as saying he tried to kidnap JonBenet for a $118,000 ransom but that his plan went awry and he strangled her to death.
Mickey Sherman, a defense attorney and CBS News legal consultant, said physical evidence, like the suspect's DNA, will be the linchpin in the case. "Because if that's not there, (Karr) could be nothing more than a crackpot injecting himself into this case," Sherman said. "I think they need more than him saying they need to be involved."