"He towered over the guy that got shot," testified Joy Herder, referring to Ellison. Herder said Ellison reached over Allen's shoulder and fired down into the shorter man's back.
Herder's testimony largely corroborated testimony Tuesday by Allen's sister, Mecca Drake, who was nearby when her 20-year-old younger brother was shot.
Herder's testimony, however, also somewhat supported the defense claim that Ellison shot in self-defense after Allen drew a silver revolver.
Though Herder said she did not see Allen carrying or brandishing a gun, she testified that neighbors told her they saw Allen with a "silver gun" before and earlier on the day of the Nov. 17, 2008 shooting.
No gun was found around where Allen fell to the street or in a search of his Renovo Street house.
Ellison's attorney, Brian J. McMonagle, has argued that Allen's friends grabbed and hid the gun after the shooting, when Ellison and then girlfriend, Officer Robin Fortune, had left the scene and Allen was on his way to the hospital.
Allen was paralyzed after he was shot and died Feb. 15, 2009 of sepsis brought on by a urinary tract infection.
Ellison, 40, is charged with voluntary manslaughter, conspiracy and related counts for shooting Allen during the dispute in the 1900 block of Renovo Street. Fortune, 45, who was with Ellison, is charged with reckless endangerment and conspiracy.
The chain of events began about 6 p.m. when Ellison's son, Chauncey Jr., 14, and another teen went to Bruno's, a neighbor pizzeria.
Walking home, the two were accosted by a slightly older teen, Demetrius Haywood, who grabbed the pie and knocked Ellison to the ground with a punch to the head.
Ellison - his son in the car - and Fortune started driving around the neighborhood until spotting Haywood and following him to the 1900 block of Renovo Street.
Authorities say Allen, Haywood's friend, stepped in and tried to defuse the situation and offered to pay for the stolen pizza. But the argument involving Allen and another sister and Haywood and Ellison and Fortune escalated until the shooting.