'O2 Bandit' has carried an apparent oxygen tank during 3 Denver bank robberies this month, FBI says

Robber also wears medical mask

DENVER - The FBI believes a robber nicknamed "The O2 Bandit" has held up three Denver banks this month.

Investigators gave the man his nickname because he pulls robberies wearing a medical mask and appears to be carrying a mobile oxygen (O2) tank with him. Investigators don't know if the tank is real, according to a Tuesday news release by the Denver Police Department and the FBI Rocky Mountain Safe Streets Task Force.

Other than his medical gear, the robber's method is routine. He enters the banks, presents a note demanding money to the teller and then flees with the cash.

The robber is described as a black man, 50 to 60 years of age who stands about 5-feet-8-inches to 6-feet tall and has a medium build.

Investigators believe The O2 Bandit has hit the following banks

--Chase Bank, 3300 Colorado Blvd., Denver at 11:39 a.m. on 12/07/2013.

--Westerra Credit Union, 3700 N Quebec St., Denver, at 9:30 a.m. on 12/13/2013.

--Partner Credit Union, 4000 Quebec St., Denver, at 3:45 p.m. on 12/30/2013.

Bank robbery is punishable by a 20-year prison sentence for each offense and the penalty increases if a dangerous weapon is used.