Police say a man has stabbed his roommate to death at a New York City homeless shelter.

They say 62-year-old Deven Black was found stabbed in the neck Wednesday night in East Harlem.

They say the killer fled when a security guard opened the door to the room and found Black bleeding on the floor.

Police have identified their suspect as 21-year-old Anthony White, and they are searching for him. Chief of Detectives Robert Boyce says White has had psychiatric issues since at least 2013.

Residents at the Boulevard Homeless Shelter say White had threatened to kill someone for at least a week leading up to the attack. The shelter houses men with mental health issues.

Black was a former city public school teacher and librarian.