By George P. Hassett

The lawyer for a Cambridge man accused of killing a newly engaged man over a gold chain two years ago on Linden Street said his client was acting in self-defense.

Walter Norris, 22, shot and killed Bernard Johnson in self-defense on Aug. 30, while Johnson had a gun in his own hand, Norris’ attorney, Steve Neyman, said last week.

In the first week of the trial, witnesses for the prosecution testified that Johnson had a gun behind his back and pointed towards the ground when Norris appeared from the side and shot him several times after a dispute in a Linden Street parking lot.

Johnson had surprised his girlfriend with a diamond ring and a marriage proposal earlier that night, his girlfriend, Desiree Pires, said when she testified in court. Prosecutors allege the couple was at Pires’ cousin’s Somerville apartment celebrating the engagement when a man invited to the apartment by the cousin jumped Johnson for his gold chain.

Valentino Facey, 23, of Cambridge, who is also on trial for first degree murder, allegedly tried to snatch the chain from Johnson’s neck and got into a scuffle with him. The two men separated and Johnson said, ‚ÄúI can’t believe you just tried to rob me,‚Äù according to witnesses for the prosecution.

Moments later, Johnson was on the ground dead from gunshot wounds and Pires was crying over his body, witnesses testified.