PHILADELPHIA (AP) -- Philadelphia-area Muslims are offering a cash reward in a series of crimes committed by men using women's Islamic garb to conceal their identities.

An organization representing dozens of Muslim congregations is offering $20,000 in rewards following a rash of bank holdups and a homicide authorities say were perpetrated by men wearing the long robes and face scarves worn by some Muslim women.

Perpetrators wore Muslim garb in five Philadelphia bank robberies since December. A man charged with an April 18 killing in an Upper Darby barber shop allegedly wore a woman's robe as part of a robbery ruse.

Islamic leaders say they're concerned the crimes could make Muslim women the targets of mistrust or even violence.

District Attorney Seth Williams appealed for the public's help, calling the criminals "cowards."