The FBI is looking for the so-called Portfolio Bandit, a robber who gives tellers notes he takes from a black portfolio folder.
He is suspected in 11 bank robberies in the Denver metro area from December 2008 and Feb. 3, when he is suspected of robbing the US Bank at 1560 South Pierce St. in Denver.
In three of the robberies he indicated he had a weapon, but tellers did not see one, the FBI said in a statement.