Spokesman Gary Harris told MSNBC that the family believes John Mark Karr was with his ex-wife and three sons when the slaying was committed on Christmas 1996, the Denver Post reported Thursday.
When asked why Karr would confess to the killing, Harris said: "John Karr is a bragger. He wants fame and notoriety ... and often hallucinates and likes to lie."
"He's not as he's been portrayed," Harris said. "He's no creature of the dark. There's a lot of good inside of him. He would not kill a child."
Harris said the family had not heard from Karr since he was arrested for child pornography in 2001, and had thought he might be dead.
"He has had mental problems. He's a disturbed person, but not a killer. I'm convinced he'll be completely exonerated."
Harris said the family was searching for pictures of Karr taken on Christmas in 1996, but so far none had been found.