The D.C. medical examiner is investigating the death of a man whose body was discovered at the entrance to the L'Enfant Plaza Metro station yesterday afternoon.

Metro spokeswoman Cheryl Johnson said that about 1 p.m. the station manager noticed a man lying on the ground near the escalators at the southeast corner of Ninth and D streets SW.

She said that the man appeared to be sleeping and that the station manager called Metro's Transit Police to have him removed. "We don't allow people to lie around like that," Johnson said.

An officer who responded tried to rouse the man and checked his vital signs before calling an ambulance, Transit Police Chief Polly Hanson said. Paramedics tried to revive him, she said.

The man appeared to have died of natural causes, Hanson said.

Authorities said that while his body was discovered near the bank of escalators, they don't believe the mechanical devices played any role.

The officer had spotted the man earlier in the day walking near the Metro station, Hanson said.

The man, who was white, carried no identification, and authorities did not know his name as of last night. Transit Police visited shelters for the homeless yesterday, trying to find anyone who might know the man, Hanson said.

D.C. Chief Medical Examiner Jonathan L. Arden said the cause of death had not been determined. He said that he would perform an autopsy today or tomorrow and that he hoped it would help determine why the man died and how long he had been dead.

Metro board Chairman Jim Graham, who also serves on the D.C. Council, said he plans a thorough investigation into the death.

"As a homeless advocate and chairman of the Metro board, I wanted to assure people that this would be the subject of a very thorough investigation. . . . The important message is that we care very deeply about every human life. We all have a responsibility in terms of the homeless."