A Philadelphia jury has sentenced a confessed cop killer to death for fatally shooting a police officer during a robbery two years ago.

The jury deliberated for two hours Tuesday before condemning 23-year-old John Lewis to death in the slaying of Officer Chuck Cassidy.

Defense lawyers described the baby-faced Lewis as a young man deserving of mercy. They said he lost his father to violence at a young age.

Cassidy, a 25-year police veteran, was shot in the head as he walked in on a robbery at a North Philadelphia doughnut shop on Oct. 31, 2007. He died the next day.

Lewis entered a surprise guilty plea to a general murder charge after jury selection earlier this month. The jury convicted him of first-degree murder last week.