A US man arrested in Thailand is being held in connection with the murder 10 years ago of American child beauty queen JonBenet Ramsey.
Many thought that the case would never be solved
The Ramsey family's lawyer said he had confessed to some elements of the crime and US media say he is expected to be extradited shortly.
The man was first arrested on unrelated sex charges, officials said.
JonBenet, 6, was found strangled in the basement of her Colorado home in 1996 in a case which gripped America.
The suspect has been identified by US media as John Mark Karr, 41, a former second-grade (children seven to eight years of age) schoolteacher.
It is not known whether the man has any connection to the Ramsey family.
Boulder, Colorado, District Attorney Mary Lacey said the arrest had followed "several months of a focused and complex investigation".
JonBenet was found beaten and strangled in the basement of her family home in Boulder, Colorado.
Her family, who later moved to Atlanta, Georgia, have fought for years to clear their names of persistent accusations of involvement in the death of their daughter.
Their lawyer, Lin Wood, said the Ramseys had learned about the suspect at least a month before JonBenet's mother, Patsy Ramsey, died of cancer in June.
"It's been a very long 10 years and I'm just sorry Patsy isn't here for me to hug her neck," Mr Wood said.
John Ramsey, the murdered girl's father said in a statement:
"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."
Bronson Hilliard, managing editor of the Colorado Daily newspaper, told the BBC that the case had affected people all over the world.
"Probably once a month someone around the world calls and tells me that they've solved the JonBenet Ramsey case," he said, speaking to BBC Radio Five Live.
"I'm very much looking forward to those phone calls ending.
"It is the sort of case that people made their minds up on based on imagery, based on media reports, based on a lot of superficial information and it would prove to be quite tragic for all concerned."