The badly decomposed bodies of a woman and an infant, apparently her child, were discovered Sunday night and early yesterday morning in the bedroom closet of a Baileys Crossroads apartment.

Fairfax County police said yesterday the deaths were either murders or a murder-suicide and said investigators were calling them "unclassified suspicious deaths" until laboratory tests on the victims are completed.

Police spokesman Warren Carmichael said officers were unsure of the identity, age, and cause of death of the woman or the infant -- whose sex was not yet determined -- because of the length of time they had been dead. The infant's body was not discovered until early yesterday morning when investigators, wearing gauze masks because of the odor, moved the woman's body and a blanket that partly covered it.

Neighbors and officials in the building at 3606 Barcroftview Ter., off Columbia Pike, said that Apartment 101, where the bodies were found, is rented to Terry Lee Simmons and Caroline H. Yoo. A Korean native, Yoo has a 5-month-old daughter, Julie, the neighbors said.

Deputy Fairfax County prosecutor Steven A. Merril said last night that investigators were uncertain if the couple was married, but that they believed the dead infant was Yoo's daughter. "Everything is under investigation," Merril said. "The case is really in the initial stages of investigation."

Merril said police had not issued any warrants in the case.

One neighbor, who asked not to be identified, said she had not seen Yoo or the infant in about a month and a half, and assumed that Yoo had left Simmons, whom neighbors described as a military man, because the couple had been having "marital problems." A neighbor did say, however, she had seen Simmons as recently as Thursday night.

A Military Police source said last night that Yoo had served in the Army and was honorably discharged in February because of pregnancy.

The bodies were discovered when neighbors, returning to the three-story apartment building around 7 p.m. Sunday, noticed the window of Apartment 101, which is slightly below ground level, was covered with flies on the inside. Once inside the building, the neighbors detected an odor and alerted the resident manager of project.

The resident manager made a search of the apartment, and discovered the blanket-covered body of the woman. She called police.

Carmichael said the two bodies had been in the apartment closet "at least several days," but he said he could not be more precise.

The apartment manager said that Simmons and Yoo moved into the $400-a-month, two-bedroom apartment in February, and had paid their rent regularly. The manager also said she believed Simmons worked in the Pentagon and that the couple had no child at the time they moved in.

"We just assumed that she had left him," one neighbor said. The neighbor explained that Simmons and Yoo, who are in their mid-20s, were known to have a discordant relationship. On one occasion, she said, Yoo was seen leaving the apartment with a suitcase, only to return that night.

She said that Simmons and Yoo usually kept to themselves, and that nobody in the apartment building knew them very well.