A Bostonthief has perfected a disciplined form of bank robbery that has him in and out of a bank in around 30 seconds. The "U30 Bandit" is now the subject of a massiveFBI manhunt.

Between March 26 and June 16, he has struck at 7 banks in the Boston suburbs.6 are charted out on this map.

He is known to wear a hood, baseball cap, glovesand/or ski mask, and in some cases, a Halloween skull mask or dread-lock wig.In three cases, the robber placed what appeared to bean explosive device--three wired sticks of dynamite--on a teller's desk.

An FBI spokesman said, "He's obviously becoming more aggressive, and that concerns us."

The FBI has offered a $37,500 reward for the arrest of the man. No further physical description has been made public, other than he is white, around 5'10 and flees in a getaway car with an unknown accomplice.

Anyone with information pertaining to the bandit is enouraged to call the FBI tipline at 617-742-5533.