New Castle police said the woman opened her inside door when she heard a knock Friday evening and she saw a man who then pulled on the outside door and broke the chain, the New Castle News reported Thursday.
The woman told police the man asked her for money and she gave him $5, but he pushed past her and took $20 from her purse.
"I'm sorry, I've never done this before. I'm desperate," the woman quoted the robber as saying.
The woman said she began to pray and the man knelt down on the floor until she was finished, the newspaper reported.
Police said a Shenango Township officer spotted a man matching the robber's description and was able to retrieve his dropped backpack while giving chase.
Investigators said they used documents from inside the bag to identify the suspect and Christopher Perretti, 32, was arrested Saturday.
Perretti was charged with burglary, robbery, theft and receiving stolen property. He was taken to the Lawrence County Jail in lieu of $5,000 bond, the News reported.