“You now know beyond a reasonable doubt, not from what I say or from what anyone else says but from RICHARD FRANKLIN’s own words, that 30 years ago he went to rob Gregory McDavid and shot him instead,” a Suffolk County prosecutor told a Superior Court jury during closing arguments in Franklin’s homicide trial.

Franklin (D.O.B. 11/20/61) is charged with manslaughter for allegedly shooting the 30-year-old McDavid to death on May 13, 1979. 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 took responsibility for it.

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.

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.

Franklin’s statements were “calm, rational, and voluntary,” Assistant District Attorney Ian Polumbaum said, and came from personal knowledge – not recollections of media reports or word on the street.

“He could not and did not get that level of detail from the news,” Polumbaum told jurors.

Among the points of similarity between Franklin’s statements and the accounts of police investigators, eyewitnesses, and medical examiners, Polumbaum said, were McDavid’s efforts to sell marijuana to friends that day; the position McDavid took within the car when he saw Franklin approaching; the route McDavid took out of that car and into a nearby residence once shot; his clothing and general appearance; the route that he himself took when fleeing the scene, including the presence of eyewitnesses who later spoke to police; and the type of handgun used to kill McDavid.

“This was a rational, coherent, and fact-based account that he gave,” Polumbaum said. “[Franklin] initiated this contact. Nothing in those statements suggests a delusion.”

Following closing arguments, Judge Judith Fabricant instructed jurors on the relevant law. They will deliberate until they reach a unanimous verdict.

Franklin is represented by attorney James Coviello.