A District Heights man has been convicted of first-degree murder for the 2001 slaying of a man with whom he sold drugs, authorities said Monday.

Billy Joe Simon, 42, now faces the possibility of life in prison for the June 10, 2001, slaying of 27-year-old Michael Neal, authorities said. The two men were both drug dealers, and Simon apparently shot and killed Neal during a home invasion robbery, prosecutors said.

Prosecutors said DNA was key to winning the conviction. Simon, they said, left blood smears on the walls and stairways of Neal’s Upper Marlboro townhouse after the shooting and robbery, and investigators were able to match DNA from that to samples taken from Simon after a separate conviction in D.C. in February 2011. He was charged in Neal’s death in May of that year.

Prosecutors said Neal had been lying in bed with his fiance — their one-month-old son in a bassinet nearby — when Simon and another masked man broke in and shot him. Simon and the other man took cash and fled the scene, leaving Neal’s wife, son and a 12-year-old daughter who was elsewhere in the home unharmed, prosecutors said.

John Erzen, a spokesman for Prince George’s State’s Attorney Angela Alsobrooks, said he did not know whether investigators had been able to track down the other attacker.

Simon’s sentencing is scheduled for June 22, prosecutors said.