Aug. 17 (Bloomberg) -- American John Mark Karr told Thai police he accidentally killed JonBenet Ramsey, a 6-year-old girl found slain in the basement of her family's Colorado home almost a decade ago, officials said.

Karr, 41, was arrested at his Bangkok apartment yesterday on first-degree murder charges, Police Lieutenant General Suwat Tumrongsriskul said during a press briefing with U.S. authorities. Autopsy reports showed JonBenet had been strangled with a rope and her skull had been fractured.

``I loved JonBenet very much,'' Karr told reporters as he was brought into a Thai immigration detention center. ``Her death was an accident.''

The investigation into what role Karr may have played in JonBenet's death is still under way, Boulder County District Attorney Mary Lacy said during a press conference today. She declined to comment on what evidence led to Karr's arrest and repeated that he is to be presumed innocent.

``There is much work to be done,'' Lacy said. ``The analysis of the evidence in this case continues on a day-by-day, hour-by- hour basis.''

Dec. 26, 1996

JonBenet was found dead by her father on Dec. 26, 1996, after earlier being reported missing. Footage of JonBenet competing in beauty pageants was shown across the U.S. as the Ramsey family and police sparred over how the investigation was handled. While the police focused on the parents, John and Patsy Ramsey maintained an intruder killed their daughter.

``Karr has been very cooperative,'' Ann Hurst, the U.S. Department Homeland Security attache in Bangkok, said during the briefing. ``He expressed surprise when we arrested him. His first reaction was he questioned our right to detain him.''

Lacy suggested Karr's arrest may have been forced by concern for public safety or fear he would flee. She wouldn't comment further.

The arrest warrant for Karr included kidnapping and sexual assault charges, Hurst said during the briefing. He will be moved to the U.S. within the next week, she said.

Details on how Karr may have known JonBenet weren't available. The Ramsey family didn't know Karr, JonBenet's aunt, Pamela Paugh told CNN.

Ex-Wife's Alibi

While Karr said he was with JonBenet when she died, his ex- wife, Lara, said he was with her throughout the 1996 Christmas season in Alabama, where the Karr family lived at the time, the Associated Press reported.

There is no listing for John Karr in Colorado. Calls to two residential listings for John Karr in Georgia, where the Rocky Mountain News said Karr used to live, weren't returned.

Karr became a focus of the investigation after he e-mailed Michael Tracey, a University of Colorado journalism professor who produced three documentaries on the Ramsey case, university spokesman Barrie Hartman said.

``They did talk about the case, and what this man said led Michael to continue the conversation and led him to contact the authorities,'' he said.

U.S. and Thai authorities worked together for more than two months to locate Karr, who has been away from the U.S. for three years and has been in and out of Thailand five times since 2005, Hurst said.

In May, police and federal agents in Georgia were called in to help identify and locate Karr, said Sergeant James McGee of the Roswell, Georgia, police department. Their efforts included officers assigned to a task force working to combat child pornography, he said.

Second-Grade Teacher

Karr had started work Aug. 15 as a second-grade teacher in an international school in Bangkok, Lacy said. Karr was arrested in March 2001 on child pornography charges in Sonoma County, California, Denver television station KUSA reported, citing the district attorney's office there.

Patsy Ramsey died in June of ovarian cancer after battling the disease since 1993. Karr told AP he had written to her before she died.

``Patsy was aware that authorities were close to making an arrest in the case and had she lived to see this day, would no doubt have been as pleased as I am with today's development almost 10 years after our daughter's murder,'' John Ramsey said in a statement yesterday.

To contact the reporters on this story: Courtney Dentch in New York at cdentch1@bloomberg.net; Anuchit Nguyen in Bangkok at anguyen@bloomberg.net.

Last Updated: August 17, 2006 16:17 EDT