"Mark Wallace was murdered, and don't let anybody else tell you different," Lim said, adding that the Shaffers "completely set the tempo and their aggression was obvious to everyone."
But defense attorney Coley O. Reynolds described Shaffer, 23, as the victim caught between his volatile, violent father and the inebriated, violent Wallace, 54.
Reynolds said the evidence would show that "Big Gerry was, quite frankly, just a bully" with an explosive temper that often led to fist fights. He also beat his sons, Reynolds said.
The attorney said the younger Shaffer tried to intervene in the fight between his father and Wallace. He said Wallace accidentally struck his head when Shaffer grabbed him in a bear hug and they fell to the ground.
Shaffer is on trial for third-degree murder. His father - a 23-year veteran city firefighter - was also charged, but died Dec. 5, 2011, at home of a heart attack at 48.
A short man with glasses and a buzz cut, Shaffer wept continuously through the opening statements and first witnesses, pulling one tissue after another from the box on the table before him.
The incident that ended with Wallace's death began about 7:30 p.m. April 8, 2010, at Knights and Fairdale Roads in the Northeast.
Witnesses testified that Wallace was crossing Knights at the light and walked in front of Shaffer Sr.'s gold SUV.
Shaffer began honking his horn and swearing at Wallace to get out of the way. Wallace yelled back, "I have the right of way."
Justine Braciszewski, 22, standing at the intersection's southwest corner, said Shaffer Sr. parked the SUV, got out, and pursued Wallace.
Wallace held his hands up and backed away, Braciszewski testified, still saying he "had the right of way." She said Shaffer pushed Wallace in the chest and knocked him back several steps. Wallace then approached and threw a punch, and the pair started fighting.
Braciszewski said Shaffer Jr. got out of his vehicle and ran to the fight, calling after his father.
Braciszewski testified that Shaffer Jr. pushed his father out of the way and grabbed Wallace from behind in a bear hug. He then flipped Wallace over his shoulder and headfirst into the concrete.
"Mark didn't move after that," she added.
Both men got back into the SUV and drove off. Wallace died two weeks later of massive brain injuries.
Another witness, Jean Janukowicz, said she saw Shaffer Sr. drag Wallace by the coat collar and drop him face-first to the ground "like a sack of potatoes."
Janukowicz, who wept as she recalled the incident, said Shaffer Sr. stared at her and walked away when she told him she was calling 911. She went to Wallace, who was not moving but moaned.
"He said, 'Please help me,' " Janukowicz told the jury.
Contact Joseph A. Slobodzian at 215-854-2985 or firstname.lastname@example.org, or follow on Twitter @joeslobo.