Kalogerakos was last seen by his roommate in Idaho City, Idaho on December 28, 2007. His roommate evicted him from their trailer that day. He has never been heard from again. His mother and sister in Chicago, Illinois reported him missing after they hadn't heard from him in a week; prior to this, he had daily contact with them. Kalogerakos may have been seen in Boise, Idaho after his disappearance, but this is unconfirmed. He had moved to Idaho three months before he went missing.

Kalogerakos told his family he had been fighting with his roommate and his girlfriend prior to his disappearance. He left behind all his belongings and his car. Although there is no indication of foul play in his disappearance, authorities believe he may be dead. His case remains unsolved.

Some agencies give the date of Kalogerakos's disappearance as December 25, 2007.