“Gregory McDavid has been dead as long as he was alive,” Assistant District Attorney Ian Polumbaum said today during opening statements in the trial of RICHARD FRANKLIN (D.O.B. 11/20/61) for McDavid’s 1979 shooting death.

“You will learn that Mr. Franklin got away with the killing that day, that month, that year, and for 16½ years,” Polumbaum continued, “until 1995 when by his own admission his conscience got the better of him.”

Franklin is charged with manslaughter for shooting McDavid as the 30-year-old Jamaica Plain father sat in his car on a Dorchester street on the afternoon of May 13, 1979. The crime went unsolved until Franklin confessed to it, first to a community service officer at his Brockton housing development and later to Boston Police homicide detectives.

Investigators believe that McDavid had been selling or offering to sell marijuana at a nearby residence when he walked “downstairs to his car, a Mercury Monarch four-door with a red interior,” Polumbaum said. “At that time, a young man approached the car, pointed a handgun at Mr. McDavid, and fired a single shot through the closed window.”

A nearby witness doing yard work saw a “young man” approach the car and point “something” at the window, Polumbaum said.

“He realized after hearing the gunshot what that young man was carrying,” the prosecutor told a panel of 16 Superior Court jurors.

Mortally wounded, McDavid made it out of the car, up a flight of stairs, and into a nearby apartment, where he collapsed and died of his injury. A medical examiner at the time found that the bullet went through his lung, his heart, and two major blood vessels before travelling downward through a vein and killing him.

The assailant fled down nearby Dakota Street and through a schoolyard and was not seen again.

“Nobody was arrested, nobody was charged, and the case went cold,” Polumbaum said.

That all changed on Dec. 30, 1995, when the alleged killer approached his apartment building’s community service officer.

“Richard Franklin came in and said he wanted to get something off his chest – something he did a long time ago,” Polumbaum told jurors. After listening to the officer’s recitation of his Miranda rights, Franklin said that “he went to try to rob a man in Boston and he shot him.”

The community service officer contacted Brockton Police, who dispatched a detective. That detective also Mirandized Franklin and heard his statement, in which Franklin indicated that someone had told him McDavid was a drug dealer and given him a gun to rob McDavid. When Franklin thought McDavid was reaching for a weapon, he shot the man. He later found out that McDavid had died.

The Brockton detective contacted Boston Police and asked if they had an unsolved homicide in that time and place with a similar fact pattern. Boston Police told him they did and sent homicide detectives to interview Franklin.

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.

Franklin is represented by attorney James Coviello. Prosecution testimony is ongoing before Judge Judith Fabricant in courtroom 817.