WINCHESTER, Mass. -- Law enforcement throughout across the state is on the lookout for a bank robber who has hit nearly a dozen banks.

NewsCenter 5's Amalia Barreda reported that the bank robber hit the Sovereign Bank in Winchester on Oct. 4. A security camera captured a clear picture of his face.

"He walks in, he hands the teller a note. Which asks (the teller) to give him the money. Asks for denominations and he states on the note he has a gun. He will take the cash at that point, turn around and walk out. At no time does he do anything to draw attention to himself," said Winchester police Lt. James Pierce.

Police said the mystery bank robber has hit 11 banks in communities across Essex and Middlesex counties since Sept. 26. The FBI is assisting North and South Shore officials in the search.

The robber is described as having a thin build, in his early- to mid-20s, about 6 feet tall with short brown hair and glasses. He always wears a baseball cap.

"The problem we're having is he is so average, he goes unnoticed. As long as he goes about his business in a normal way in a bank, he's no different than any other customer would be in that bank," Pierce said. "He's a cool customer. He doesn't show any signs of nervousness."

Pierce said the robber frustrates police.

"Somebody must know who this gentleman is. He can be a neighbor, he can be a colleague in a work place," he said. "He's average, but he's not that average, so somebody has to know who this gentleman is."

Police have not said how much money the bank robber has gotten away with.