PICKENS, S.C. -- Detectives said after an interview with confessed killer Gary Michael Hilton, they are convinced he is not a suspect in the 1998 disappearance of Clemson student Jason Knapp.

Pickens County detectives made the announcement during a news conference on Tuesday morning. During the same meeting, investigators released the audio from the interview as well as a letter written to the detectives by Hilton.

Detectives had hoped that an interview with Hilton would solve Knapp’s disappearance.

Knapp disappeared in April 1998. His car was found at Table Rock State Park nine days after he disappeared. The park is only 45 minutes from Brevard, N.C., where Hilton is accused of kidnapping and killing John and Irene Bryant.

During the interview, Hilton admits he is familiar with Knapp’s case but only through media reports. He also admits knowing about Table Rock State Park.

Hilton also speaks directly to Knapp’s mother during the interview.

“I can shed no light on your son’s disappearance,” Hilton said. “I know what you are going through.”

Hilton’s letter is addressed to the two detectives who interviewed him on April 17. Hilton said he liked both of the investigators and that he was impressed with their ability.

Hilton went on to talk about three things he believes may have happened to Knapp. First, Hilton said Knapp’s body may be at the base of a mountain and missed in the initial search. Second, Hilton said Knapp may have fallen while hiking and his body is lodged on a ledge of a mountain. Third, Hilton said Knapp may have been attacked and eaten by bears or coyotes.

“I hope that as a result of this letter and our interview that you will have some good thoughts of me and understand that I’m not all bad,” Hilton wrote.

Hilton ends the letter by calling his knowledge of Table Rock State Park as an “understandable coincidence.”

Detectives said they released the interview and letter to give the public a glimpse of the nature and thought process of Hilton. They said they also hope to bring attention to a case that has gone cold.

Anyone with information on Knapp’s disappearance is asked to call the Pickens County Sheriff’s Office.