D.C. police are investigating the death of a 38-year-old man who stopped breathing while being subdued by two workers he allegedly held up in Southeast Washington.

Winston R. Smith of no fixed address died Tuesday after the incident in the 4000 block of Third Street SE, police said. The D.C. medical examiner yesterday ruled the death a homicide, authorities said.

No arrests were made, and police said they are referring the case to the U.S. attorney's office to decide whether charges will be filed.

Police said the trouble began Tuesday afternoon when Smith sought employment from two workers who were installing video surveillance equipment at an apartment complex on Third Street SE. After helping with the job and being paid for his labor, Smith left, police said.

He returned just before 3 p.m., claiming to have a gun hidden under a stocking cap in his hand and demanding money, police said.

After Smith robbed one of the men, police said, the workers discovered that Smith didn't have a gun.

Police said the workers, whose names were not released, chased Smith and held him on the ground until officers arrived.

Smith was unconscious when officers reached the scene, and paramedics took him by ambulance to Greater Southeast Community Hospital, where he was pronounced dead.

Police said the D.C. medical examiner ruled the death a homicide after an autopsy determined that pressure on Smith's chest and neck led to asphyxiation.

The two men are employed by Accel Inc. of Gloucester, Va., authorities said. A woman who answered a call made to the company yesterday declined to comment.