Opening statements were delivered Wednesday in the trial of a former traffic police officer accused of killing a drunken driver.

Prosecutors say former Officer Rafael Lora intended to hurt Fermin Arzu in November 2007, when he shot the man in the heart five times on Longwood Avenue.

Lora's defense attorney, Stuart London, insists his client was protecting himself from an out-of-control drunk driver who refused arrest.

"He identified himself as a police officer and had his shield affixed to his waist," London says. "The last thing he wanted to do was have to use his weapon."

Lora, who is facing manslaughter charges, is expected to take the witness stand later on in the trial. Both the defense and the prosecution say the 911 call the officer made at the time of the shooting will be key evidence in the trial.

If convicted, Lora could face up to 25 years in prison.