A 31-year-old Southeast man was shot and fatally wounded in his home yesterday in an apparently drug-related slaying by a gunman posing as a mail carrier, D.C. police said. Later, in a search of the victim's home, police said they discovered more than $500,000 worth of heroin, $300,000 in cash and a small arsenal.

Police said Joseph M. McCray Jr. was found lying in the front yard of his home at 2005 32nd Place about 2:45 p.m. by neighbors, who said they had heard several reports from a gun.

Police said McCray's assailant, dressed as a mail carrier and carrying a small package, walked up the front steps of McCray's home and rang the doorbell.

When McCray answered the door, the man stepped inside, produced a handgun and fired, hitting McCray once in the face, police said.

McCray tried to run from the house, and the gunman fired at least two more shots while standing on the steps, striking McCray in the back. The assailant then ran into a wooded area, emerging on a street where he escaped in a waiting car apparently driven by another person, police said.

Investigators said they later found a blood-stained shirt and other articles of clothing that appeared to be part of a mail carrier's uniform discarded near McCray's home. It was not known whether the assailant was injured in the attack.

McCray was taken to Greater Southeast Community Hospital where he was pronounced dead at about 4 p.m. Police said an autopsy is scheduled for today.

McCray apparently was at home alone with his 10-month-old son when he was shot, a neighbor told a reporter last night. The child, who was later seen being carried from the house by a police officer, was not injured.

Police obtained a search warrant for McCray's home late last night and said they found the cash, the heroin, described as being of high quality, plus six guns and a large amount of ammunition. Police said the seizure of cash and drugs was one of the largest ever reported in the District.

Martha Mattison, who lives across the street from McCray's home, said she heard loud noises, but dismissed it until a friend who had been visiting her told her that someone had been shot.

"I thought it was a car backfiring," Mattison said, "so I didn't pay any attention until my friend who was using the phone downstairs told me to call an ambulance."

McCray, who was described by neighbors as quiet and friendly, moved into the house about two years ago and lived there with his wife, elementary-school-aged daughter and infant son.

Police said the slaying appeared to be a drug-related execution, but they said they have no suspects in the case.