But an attorney for defendant John Lewis painted a different scenario, saying his client panicked that day in a doughnut shop two years ago and did not have enough time to form an intent to kill.
Now a jury must decide whether Lewis, 23, is guilty of first-degree murder, which could lead to the death penalty, or second-degree murder, which brings an automatic life sentence. Deliberations began Thursday afternoon after closing arguments.
Lewis pleaded guilty last week to a general charge of murder in the shooting of Philadelphia police Officer Chuck Cassidy on Oct. 31, 2007. Lewis was robbing a Dunkin' Donuts - his sixth robbery in six weeks - when Cassidy walked in.
Surveillance video shown in court depicts Lewis turning from the counter and stepping toward Cassidy before shooting him in the head. Cassidy, a 54-year-old father of three, died the next day.
The encounter between the two men took no more than two seconds, Coard said, meaning the shooting could not have been "willful, deliberate and premeditated" - the requisites for first-degree murder. Second-degree murder is an unplanned death that occurs during a crime.
Coard said the prosecution's own eyewitnesses used words like "jittery," "surprised" and "startled" in describing Lewis' demeanor when the officer arrived.
"This was nothing more than a panicky reaction," said Coard.
But Assistant District Attorney Edward Cameron said it only takes a fraction of a second to form intent. A professional baseball player takes less than a second to decide whether to swing at a pitch - about the same time it takes someone to decide to swat at a mosquito, Cameron said.
He said Lewis had been interrupted by customers during other robberies but did not shoot them because they posed no threat. Cassidy was different, said Cameron.
"It boils down to that video," he said. "There can be no doubt of the defendant's intent that day."
The proceedings held little of the drama and surprise seen in court over the past week, starting with Lewis' unexpected guilty pleas to murder, robbery and other charges Nov. 12. Subsequent days included sometimes tearful testimony from his victims, followed by the officer's widow appearing on the witness stand Wednesday.
In the midst of her testimony, the court was stunned by an outburst from Lewis.
"I apologize, Mrs. Cassidy," he said, crying at the defense table.
Still, Coard exhorted the jury Thursday not to be swayed by the emotional testimony and evidence - including the officer's bloody shirt and badge - presented during the trial.
"You are outraged at the death of a police officer, and you should be," Coard said. "(But) what does the sympathy factor have to do at all with whether or not this is first-degree or second-degree?"
Cameron, holding the weapon used to shoot Cassidy, argued that a loaded handgun with hollow-point bullets shows Lewis' intent was "different than an ordinary robbery."
"It sends a message - you resist, you die," the prosecutor said. "This is the defendant's intent."