In court Thursday, prosecutors disclosed that DNA on the sweatshirt matched that of John Lewis - the 21-year-old charged with fatally shooting the officer during an Oct. 31 robbery of the same Dunkin' Donuts.
"It's just a sad situation," a store clerk, Cynthia Beckwith, testified at the end of the first day of a hearing to determine if Lewis should stand trial.
Lewis, the son of a prison guard, is charged with a short but increasingly violent string of store robberies in Northeast Philadelphia last fall that culminated with the police slaying.
Employees of two pizzerias and several Dunkin' Donuts shops gave similar accounts Thursday of how a chubby-cheeked man in a dark, hooded sweatshirt approached the counter, nervously waved his gun and demanded money from multiple cash drawers.
Employees of one pizzeria recognized him as a regular and thought he was joking. But there was no such confusion Oct. 25 when a more assertive gunman ordered employees - and their children in the office - into a huddle, took money from their pockets and then fired a shot into the floor.
Nearly all of the witnesses Thursday had picked Lewis out of a police photo spread. But defense attorney Michael Coard noted they did so only after seeing his picture on TV reports about Cassidy's death. Lewis is charged with murder, six armed robberies and related charges.
Cassidy, a 54-year-old father of three, checked in on one of the Dunkin' Donuts at least once a day. The store had been robbed repeatedly.
If she didn't know his name, Beckwith knew how the patrolman took his coffee.
"(I knew him) just by coming into the store and ordering 'four sugars and cream,"' she said, eliciting a half-smile, and glistened eyes, from the officer's widow, Judith Cassidy.
She sat in the front row with her son and two daughters, while a phalanx of uniformed officers filled the courtroom. New police Commissioner Charles Ramsey, in just his fourth day on the job, came to court to greet the family.
Beckwith was perhaps the first person to call 911 about the Sept. 18 robbery, when the sweatshirt was recovered. She was getting into her car after work when her sister, a co-worker, called from inside to report the holdup. Beckwith called 911, watched the suspect leave and then tailed him in her car until he ran in an alley. When Cassidy arrived, she showed him where he had ditched his sweatshirt.
"My sister was frantic, and I recently lost my brother, so I just wanted to do something about it," Beckwith said, explaining her unusual response.
Six weeks later, Beckwith was coming out of the bathroom at work when she heard a "pop" and soon realized Cassidy had been shot. She saw the suspect flee, and ran to Cassidy to tend his wound.
He had been shot once in the temple as he walked in on the latest robbery.
This time, Beckwith only saw the suspect from behind as he fled.
But as she held some tissue to Cassidy's head, she thought about his frame and gait. She said she thought to herself: "That's the same person that robbed us on the 18th."
Lewis was captured at a Miami homeless shelter after a weeklong manhunt. A cousin, Hakim Glover, has since pleaded guilty to charges that he bought him the bus ticket and advised him to hide two guns, allegedly the murder weapon and the officer's weapon.
More details about the day of the shooting are expected Friday when the preliminary hearing continues.
Coard, the defense lawyer, said that he may seek a plea agreement after weighing the evidence against his client.
"He's as despondent and depressed as any human being would be facing such serious charges," Coard said.
