(CNN) -- A suspect has been arrested "for the December 26, 1996, murder of JonBenet Ramsey," the district attorney in Boulder, Colorado, said Wednesday.
A law enforcement source identified the suspect as 41-year-old John Mark Karr, a one-time school teacher and American citizen who has lived in Conyers, Georgia.
It is the first arrest in the decade-long investigation of child beauty pageant contestant's slaying. The breakthrough came as a surprise to many who feared the case might never be solved.
Karr was arrested in Bangkok, Thailand, following "several months of focused and complex investigation," District Attorney Mary Lacy said.
JonBenet's parents, John and Patsy Ramsey, were consulted during the investigation, Lacy said, and the Ramsey family was notified of the arrest. Patsy Ramsey died in June of ovarian cancer at age 49. (Watch how the suspect's name surfaced -- 1:29)
Two law enforcement sources told CNN that Karr also was under investigation for an unrelated sex crime.
Karr was arrested Wednesday morning and has confessed to certain elements of the crime that are unknown to the general public, CNN affiliate KUSA reported.
An investigator with the Boulder County District Attorney's office is bringing Karr to Colorado from Thailand. Prosecutors plan to hold a news conference in Boulder on Thursday.
JonBenet's beaten and strangled body was found in the basement of the family home in Boulder, the day after Christmas in 1996. She was 6.
An autopsy determined she had received a massive blow to the head and was strangled with a garrote made from a paintbrush.
The Ramseys said an intruder committed the crime, but they remained the subject of suspicion and speculation. A grand jury investigation into the slaying of the child beauty pageant winner ended with no indictments.
Law enforcement officials said Karr was not known to investigators at the time. A warrant for his arrest was issued Tuesday night.
With no known suspect, the Ramseys remained the subject of suspicion and speculation and the case provided years of fodder for the news networks and the tabloids. At one point the Boulder police said the Ramseys were under "an umbrella of suspicion."
"It is our hope that this arrest will bring some closure to the Ramsey family after a 10-year ordeal," said the family's attorney, Hal Haddon.
John Ramsey released a statement Wednesday. He said that his wife knew when she died that an arrest might be coming.
"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," Ramsey said. (Read the full statement)
Another attorney, Lin Wood, said that although the family knew and hoped this day was coming, relatives were still not emotionally prepared for it and were working through those emotions.
"We may be, and I say may be, one step closer to the final resolution of the case. But again, I would urge that Mr. Karr be given the presumption of innocence," Wood said.
In 2003 a federal judge dismissed a lawsuit against the Ramseys, blaming the police and the FBI for bungling the investigation. The Boulder County District Attorney's Office concurred with the judge's opinion the following month, saying there was little evidence against the couple
The Ramseys left Colorado and had a house in Charlevoix, Michigan, where John Ramsey unsuccessfully ran for office in 2004.