A U.S. Marine lieutenant from Corona, CA is being praised for chasing an alleged purse snatcher four blocks in downtown Boston and tackling the suspect.

A Roslindale man is charged with unarmed robbery. He's accused of grabbing a woman's purse as she walked along Beach St. Tuesday night.

Suffolk County District Attorney Dan Conley says the woman is lucky there was a Good Samaritan nearby, and even luckier he's a Marine.

[Metro Networks]