Gang members use hand signs to communicate with each other and to challenge rival members or law enforcement officers in what they call "throwing signs." After forming in Los Angeles in the early 1970s, the Bloods street gang spread to the East Coast and formed "sets." These sets include the Piru Bloods, Fruit Town Brims, and South Side Brims (in western Maryland). The hand signs in this gallery were recovered during a multi-agency investigation earlier this year. Photos courtesy of Det. Rich Keys of the Maryland State Police.