Tillman was last seen in the vicinity of Houston and Pitt Street in the New York City borough of Manhattan at 7:00 p.m. on August 10, 2005. His mother dropped him off at a school so he could take a test to determine whether he could advance to the eighth grade. He has never been heard from again. He is believed to have left of his own accord. He did not take any belongings with him.

Tillman came out to his mother as a homosexual two months prior to his disappearance, and she claims she accepted his sexuality without any problems. According to his mother, beginning in June 2005, Tillman began coming home increasingly late and began to have trouble in school. After his disappearance, she discovered that he had been talking to adult men on the internet and may have had an 18-year-old boyfriend. There have been sightings of Tillman in the West Village area of Manhattan since his disappearance. Authorities believe he is living with friends in the local area, but he could also have traveled to San Francisco, California. His case remains unsolved.