The suspect identified by KUSA-TV, Denver, as John Mark Karr was arrested in Bangkok Wednesday after he confessed -- while jailed in Bangkok on an unrelated sexual assault case -- to killing the 6-year-old beauty queen.
Some of the details provided by Karr were never publicly released, authorities said. He was expected to arrive in Boulder within days to face charges.
Boulder District Attorney Mary Lacy released a statement late Wednesday saying Karr was arrested "after several months of a focused and complex investigation." More details were expected to be released during a news conference Thursday.
JonBenet Ramsey was found beaten and strangled in the basement of her family home the day after Christmas in 1996.
Her parents, John and Patsy Ramsey, were early suspects in the case but were never indicted and were eventually cleared by DNA evidence.
Patsy Ramsey died in June 2006 of cancer.