A Suffolk Superior Court jury today convicted a 47-year-old Brockton man for the fatal shooting of a Jamaica Plain father three decades ago, Suffolk County District Attorney Daniel F. Conley announced.

After deliberating for approximately three hours, jurors convicted RICHARD FRANKLIN (D.O.B. 11/20/61) of manslaughter and unlawful possession of a firearm for the May 13, 1979, murder of 30-year-old Gregory McDavid. Superior Court Judge Judith Fabricant revoked Franklin’s bail until he is sentenced on June 25.

“Twelve jurors followed the facts and applied the law,” Conley said. “They listened to reason, not emotion, and returned a just verdict. Justice may have been delayed but it was not denied to Gregory McDavid’s family.”

During three days of testimony, Assistant District Attorney Ian Polumbaum introduced evidence and testimony to prove that the then 17-year-old Franklin obtained a gun with a plan to rob McDavid. When Franklin saw McDavid leaning rightward inside the car, he shot McDavid instead.

Mortally wounded, McDavid staggered from the vehicle, climbed a nearby set of stairs, and collapsed in an apartment at 33 Greenbrier St. in Dorchester. He was later pronounced dead of his injuries.

The case went unsolved for more than a decade until Franklin walked unbidden into the office of a community service officer at his Brockton housing development in 1995 and admitted his role in the shooting.

In three separate post-Miranda statements to the community service officer, a Brockton Police detective, and finally members of the Boston Police Homicide Unit, Franklin admitted to approaching McDavid’s car and firing a single shot through the closed driver’s side window in the course of an attempted robbery.

In the course of a tape-recorded statement, Franklin revealed detailed knowledge of McDavid’s homicide and, ultimately, was taken into custody. In 1998, however, he was deemed not competent to stand trial and was committed to a secure psychiatric facility until 2005, when medical professionals deemed him competent to stand trial.

Franklin is represented by attorney James Coviello. Fabricant will sentence him Thursday at 11:30 a.m. in courtroom 817.