For six years, Laurel police were stumped by the mysterious killing of a 21-year-old man who was found crumpled on his mother's living room floor with a bullet in his head.

There were no signs of forced entry into the townhouse on Chapel Cove Court, and friends and family members told police that they could not imagine who would want to kill Ryan Mance, described as a well-dressed, articulate man who worked at Hecht's in Laurel Mall.

Each year on Nov. 12, the anniversary of his killing, his mother would distribute fliers around Laurel that read: "Please care!!!! Please help me find the person who is responsible for my son's death."

This week, police charged a former Bowie State University student in Mance's slaying, saying Jamal Seymour was linked to the killing by DNA evidence. The two men were acquaintances.

"I don't want to get specific on how they knew each other," said Sgt. Michael Pianpiano, the lead investigator in the case. Mance's mother, Patricia, could not be reached to comment.

Seymour, 25, is serving a sentence in Georgia for a 2001 robbery and assault and will be brought to Prince George's County to face a first-degree murder charge, police said.

He is a native of Jamaica who lived in Greenbelt with his mother in the late 1990s, according to police. At the time of the killing, he was a 19-year-old student at Bowie State.

News reports at the time of the killing said Mance was a Bowie State student, but the college said yesterday that it had no record of his enrollment.

According to court records, Seymour has a history of criminal charges in Maryland, some from several months before the 1999 killing. The counts include assault, burglary with intent to steal a firearm and malicious destruction of property. In March 1999, the most serious charges essentially were dropped and he pleaded guilty to malicious destruction of property, for which he served two days in jail, records show.

When the detective got the case in 2003, it was four years old and had a file that was 6,500 pages thick. Seymour was not a suspect.

Pianpiano had just attended a cold-case seminar in Annapolis and had begun to look into Laurel's three unsolved homicide cases: one from 1988, another from 1991 and the most recent -- Mance's -- from 1999.

Detectives had been investigating whether the crime was a burglary gone bad. Although they had found no signs of forced entry into the home, several personal items had been taken from Mance, and his ATM card had been stolen.

Days after the slaying, police obtained an image from a video camera of a man at a Greenbelt ATM trying to withdraw cash with Mance's bank card. The picture shows part of the face of the man, who is wearing glasses and an Old Navy jacket.

Pianpiano discovered DNA evidence in the old case file and put it into the national DNA database. Several months ago, it produced a match. Authorities had entered Seymour's DNA into the database when he was sent to prison.

Pianpiano interviewed Seymour for almost six hours at the prison. Police then enlarged the photo of the man at the ATM and talked to witnesses, who identified the man as Seymour.

Staff researcher Bobbye Pratt contributed to this report.