But the jury also found that although the Police Department had been deliberately indifferent to Tepper's prior years of excessive force on the job, that was not the cause of Panas' death.
The ruling angered William Panas Sr., who attended the trial with his wife, Karen.
During his 16-year career, Tepper, 46, amassed a handful of Internal Affairs citizen complaints for excessive force and he called 9-1-1 in disputes with neighbors dozens of times, Panas said.
"This officer should have been fired back in 1995, when he pulled guns on other children," Panas fumed. "If they terminated him for these outrageous incidents, he wouldn't have been able to get a gun."
Panas, who cried tears of joy and sorrow in February when Tepper got a life-without-parole sentence after being convicted of first-degree murder, said he had rejected a city offer of $600,000 to settle the case.
"It wasn't about the money. It was about justice. Our goal was to win total justice for our son and prove that the city was responsible for his death," he said.
"What happened in this trial was not justice. It's a way of saying the city of Philadelphia didn't do anything wrong. If somebody asked me if they should move to this city, I'd say no - especially if they have children," said Panas, a native Philadelphian.
Jimmy Binns, an attorney for the Panases, said he would go after Tepper's police pension and any other assets to put toward the judgment.
"They felt they won," Binns said of William Sr. and Karen Panas. "They would rather have had the city be found liable, but the jury spoke and they respect that decision."
Attempts to reach Deputy City Solicitor Mark Maguire, who has represented the city in the case, were unsuccessful.
On Twitter: @MensahDean