Federal and local authorities on Friday asked for the public's help in finding a serial bank robber who in just two weeks has made off with cash from four banks and attempted to rob two more.

The man tried to rob a Beneficial Bank in Center City on Dec. 11, and from there, he has hit banks around the city, from West Mount Airy to Point Breeze and Ogontz.

On Friday, the man attempted to rob the Wells Fargo Bank at 1575 N. 52d St. in the Parkside section of West Philadelphia, federal authorities said.

Authorities said that in each of the heists, the man walked up to a teller and handed him or her a threatening note. He then fled on foot with the cash.

No one has been injured in any of the robberies or attempted robberies, and the man has never used a weapon or displayed one.

His first successful job was the Dec. 15 robbery of the PNC Bank at 230 S. Broad St. Then he hit the Valley Green Bank at 7226 Germantown Ave. on Dec. 18; the Prudential Savings Bank at 1722 S. Broad St. on Monday; and the PNC Bank at 5900 N. Broad on Tuesday.

On Dec. 11, he tried to rob the Beneficial Bank at 1600 Chestnut St. but left without taking anything.

Police described the robber as African American, in his 30s, about 5-foot-10, with a medium build. He wore glasses in all but one of the heists.

Anyone with any information on the robberies can call the FBI at 215-418-4000 or the Philadelphia police tip line at 215-686-TIPS.