Mustafa Ali, 38, of Philadelphia, admitted to police soon after the crime that he killed the two armored-car guards as they serviced an automated teller machine near a busy shopping mall in north Philadelphia in October 2007.
Prosecutors are seeking the death penalty in the videotaped slayings of the two retired Philadelphia police officers, 65-year-old William Widmaier and 54-year-old Joseph Alullo.
Ali, formerly Shawn Steele, served seven years in prison for robbing several banks in the early 1990s. In opening statements Monday, his lawyers said he planned another robbery, not an execution.
Ali told police that he and Alullo exchanged fire - he got off eight shots and the guard two - after Alullo refused to put his gun down. Ali said he was retreating at the time.
"We are not suggesting Mr. Alullo is to blame," defense lawyer Marc Bookman said. "The case is about what was in Mr. Ali's mind at the time he approached these men and at the time he fired his weapon."
The defense plans to show the videotape repeatedly to argue against premeditation.
A third guard, driver Joseph Walczak, who was 70 at the time, survived and is expected to be a key prosecution witness. According to the defense, Ali did not know he was in the van.
Ali was due at work that morning but instead spotted the armored car and followed it from a prior stop at a police credit union to the Wachovia Bank ATM.
Assistant District Attorney Michael Barry portrayed the guards as hard-working family men who rose before dawn to work the early morning route. Loomis did not require its guards to wear bulletproof vests, and the men did not have them on.
As they drove toward the Wachovia at about 8 a.m., one of them noticed a black car following them, Barry said.
"Sadly ... they don't do anything," Barry said.
Ali was driving a new black Acura - and was captured with help from an alert dealership employee who remembered making the sale, largely because Ali was behind on his payments.
Ali told police he tossed the bag of ATM deposits - they typically contain little cash - as he fled.
"I want to apologize to the victims' families. I know better. I wasn't brought up this way," Ali told police in his statement, according to Bookman.
