Karis was a student at Carnegie Mellon University in Pittsburgh, Pennsylvania in 1993. He was last seen on campus on March 1, 1993. Authorities tracked Karis's credit card and telephone records after his disappearance. Investigators determined that he may have purchased a Greyhound bus ticket to New York City, New York on March 2 and possibly stayed in the city until March 4. Karis may have been in San Francisco, California on March 15, but that sighting remains unconfirmed. Karis has never been heard from again. Authorities believe he disappeared under suspicious circumstances.

Some agencies may list March 4, 1993 as the date of Karis's disappearance. California and Texas authorities are handling his investigation.