A man died after being found unconscious Sunday in the custody of special police officers in the District, and the D.C. police said they are investigating the death. Special police officers are not members of the D.C. police department; they usually are private security guards who may be permitted to carry firearms.

The man who died was identified Tuesday as Alonzo Smith, 27, of Southeast Washington. Police said they were notified about 4 a.m. Sunday of an assault that was occurring in a residential building in the 2300 block of Good Hope Road SE.

When officers arrived, they found a man handcuffed and in the custody of special police officers who were working on the block, police said. They said the unconscious man was not breathing.

The man was taken to a hospital where he later died, police said. No cause of death was released.