A Richmond man showed up unannounced at a Prince George's County police station shortly after midnight Sunday and said he strangled a pregnant Hyattsville woman nearly five years ago, police said yesterday.

The suspect, Osman Thomas Leekins Jr., 24, walked into the Hyattsville district station about 12:20 a.m. Sunday and asked to see a homicide detective because he had some information about an unsolved murder case, police said.

Saying that he was burdened by guilt over the crime, Leekins then allegedly told detectives that on Oct. 2, 1994, he attacked 24-year-old Sunita P. Johnson as she got off a bus, choked her to death and dumped her body in a drainage ditch near 44th Avenue and Wells Parkway in University Park.

Leekins, of the 2600 block of Hungary Spring Road in Richmond, was charged late Sunday with first-degree murder. He is being held without bond in the Prince George's County jail.

"There was some guilt, and he wanted to get it off his chest," said Lt. Michael McQuillan, commander of the Prince George's homicide squad.

Children playing in the area found Johnson's body the day after she was strangled. She was five months pregnant when she died, police said.

Police said Leekins had not previously been a suspect in the case, and they said they were surprised by his statement. Investigators said that the attack apparently was random and that Leekins did not know Johnson.

Although detectives are sometimes skeptical of sudden confessions, Leekins described details of the attack that had not been publicly disclosed and took detectives to the scene of the crime and showed them exactly where the attack took place, according to a statement of charges filed in Prince George's County District Court.

"He admitted his involvement, and we were convinced. Otherwise, we wouldn't have charged him," McQuillan said.

Court records show that Leekins in 1993 listed his residence as the 6000 block of 44th Avenue in Hyattsville, about four blocks from where Johnson's body was found. Investigators said Johnson was attacked after she got off a Metro bus and was walking to her home on Oglethorpe Street in Hyattsville.

At the time, police said they were investigating similarities between Johnson's death and the slaying of a Rockville woman who was found dead the next day. The Rockville woman, Le Thi Bich-Thuy, 42, also was strangled; she had been returning from the Twinbrook Metrorail station in Montgomery County, near her home. That case remains unsolved, Montgomery County police said yesterday.

Prince George's police said yesterday that they were investigating whether Leekins may be involved in other crimes but said that he was not a suspect in any specific cases.

Police said Leekins moved to Richmond in late 1994 or early 1995 with his family. Court records show that he pleaded guilty to a charge of battery in February 1996 in Prince George's County District Court and was given a 30-day suspended sentence and two years' probation.

A woman who answered the phone at Leekins's Richmond home and identified herself as his sister declined to comment yesterday and said his family did not want to be interviewed.

Metro researcher Bobbye Pratt contributed to this report.