The FBI is investigating the death of a 21-year-old Falls Church man whose body was discovered Monday in a parked car at the Pentagon.

Gregory Michael Yermack of 3152 Annandale Rd. was found lying on the passenger side of his parents' Volkswagen, according to the FBI. The cause of death was apparently a drug overdose, and needle marks were found on the victim's arm, the FBI said.

"We have information that he was a drug user," one FBI agent said yesterday. A woman who was a friend of Yermack also "indicated that he may have had some (drug) connections," the agent said.

"Right now we're investigating a possible murder, suicide or accident," the agent said.

The victim's father, Michael Yermack, said yesterday that his son had "absolutely no reason" to commit suicide. "The FBI has told us that it didn't happen there, that he was dumped there," he said. "That's about all we know."

The Yermacks last saw their son Saturday morning before a weekend trip to Ocean City, Md.

The body was found at 8:06 a.m. Monday by a Pentagon employe, the FBI said. Yermack, a recent graduate of Northern Virginia Community College, was last seen alive Saturday afternoon, the FBI said. His whereabouts between Saturday and the time of death Sunday night could not be determined, according to the FBI.

"There was no sign of trauma, no sign of a struggle or forced injection," the agent said, declining to release more details.

Authorities had not received the final autopsy report late yesterday.