Parolee Earl Ellis Green, 44, is charged with first-degree murder for allegedly hitting Officer Ryan Bonaminio in the head with a metal bar, then shooting him at least three times with his own gun on Nov. 7.
Green allegedly stole a big rig that night, hit a car and then took off running with Bonaminio in pursuit. Green is accused of ambushing Bonaminio in Fairmount Park, ignoring the officer's pleas to spare his life and murdering him in cold blood.
Green, who has a violent criminal history, is undergoing a mental evaluation. He is scheduled to enter a plea Dec. 16.
In deciding whether to seek death or life in prison without parole, Pacheco said he spoke with Bonaminio's family, as well as senior prosecutors, police investigators, defense attorneys and members of the defendant's family. Green's criminal history was also considered.
"We were struck with an obvious decision ... seeking the death penalty," the county's top prosecutor said. "This was not a close call for us. It was overwhelming."
He said Bonaminio's family was "unanimous" in its desire to see Green face capital punishment. The officer's father, Joe Bonaminio, attended the briefing but declined to comment.
Pacheco described the victim as a "hometown hero," noting his military service and two tours in Iraq.
City News Service contributed to this story.