Andrew Bullock, of Orchard Street, faces at least 10 charges in the Friday morning attack.
The nun serves at St. Titus Church on Franklin Avenue.
She was walking in a parking lot behind the church when she was approached by a man who choked her, punched her, then threw her to the ground where she was assaulted and raped.
The nun, who is in her 70s, is recovering at Allegheny General from a broken jaw.
Assistant Chief Dan Couch told KDKA’s Kym Gable, “The first thing you notice when you look up up where this horrific act occurred, is the statue of the Virgin Mary looking down.”
Couch told Gable the savage beating outraged officers in his department.
They worked with the Beaver County D.A. to make a swift arrest.
A key piece of evidence was a boot print in the snow that investigators say matches the boots Bullock was wearing.