The Bucks County District Attorney's office said on Monday that man is 33-year-old Willie Bozarth, with a last known address in Sewell, New Jersey.
Bozarth was shot and killed inside the Pennsbury Pharmacy on New Falls Road.
Police say Bozarth and another suspect, 55-year-old Kim Goldsboro, arrived at the pharmacy in a minivan.
Goldsboro waited outside while, police say, Bozarth went in armed with a shotgun.
The pharmacy owner, Kenneth Lee, saw what was about to happen through his surveillance system and, police say, warned Bozarth he was armed.
Bozarth still jumped the counter so, investigators say, Lee opened fire.
Police say the pharmacy owner will not face any charges.
"From what I can see, he performed a public service in taking out this fella," District Attorney David Heckler said at a news conference on Friday. "The fella asked for what he got and he got it."
Goldsboro waited inside the minivan, police say, and was unaware of the shooting. He was still inside the vehicle when police arrived. He was arrested on the spot.