D.C. police said yesterday that they were continuing to investigate a report that a woman threw an infant and then herself off the John Philip Sousa bridge Tuesday in Southeast, but so far they have been unable to verify that the incident occurred.

A homicide official said checks with numerous sources, including hospitals and reports of missing persons, revealed no one matching the description of the woman given by a motorist who reported the incident.

In addition, the official said, information contained in a reported separate sighting of the woman by an employe at a nearby McDonald's restaurant was insufficient to confirm that the same woman was involved in both instances.

"I have no proof that a death occurred," the homicide official said. "I can't prove it did, and I can't prove it didn't."

The incident was reported by an unidentified motorist who told police that he had picked up the woman and baby after spotting the woman hitchiking about 1:45 p.m. Tuesday near the McDonald's at 1539 Pennsylvania Ave. SE.

According to police, the motorist said he drove southeast on Pennsylvania Avenue when the woman suddenly became agitated and asked to be let out of the car on the bridge. Before the car had come to a complete halt, according to this account, the woman leapt from the car, walked to the guard rail, threw the infant over the side and jumped into the Anacostia River.

Police, who called off their search for bodies Thursday, have since become skeptical of the account, noting that the motorist, a 33-year-old security guard, did not call authorities to report the incident until reaching his home in Southeast about eight blocks away. Also, no other motorists from the heavily traveled bridge have come forward to corroborate the account.

The homicide official said that information about a woman with a child given by the McDonald's employe could apply to any of hundreds of women with small children who patronize the restaurant each day and that the sighting could not be pinpointed at the time in question.

He said the security guard has been unable to give police more than "a general description" of the woman.

Police have refused to identify the security guard, who they said works at a nursing home at 3333 Wisconsin Ave. NW. Officials for the security company, International Security Corp. in Arlington, refused to comment yesterday.