ATLANTA -- Police now say confessed killer Gary Hilton was not involved in the 1998 disappearance of a Clemson University student.

Jason Knapp’s car was found in a South Carolina state park and searches have produced no clues. Several people reported seeing Hilton near where Knapp disappeared.

Police interviewed Hilton and he assured them and Knapp’s mother that he had nothing to do with her son’s disappearance. “I’m sorry that I can’t bring you any closure ultimately,” Hilton said. “But I am glad and I hope you believe me that this is one avenue that you can close.”

Hilton pleaded guilty to killing Georgia hiker Meredith Emerson in January. He’s also suspected in the murder of a North Carolina couple in October 2007 and a Florida woman in December 2007.

Hilton is currently in Georgia serving a life sentence.