(Refiles to add pictures designation in slugline) By Brent Smith INDIANAPOLIS, **v 17 (Reuters) - The Parents of an American aid worker beheaded by Islamic State militants after his abduction in Syria asked for prayers for other captives in Syria and Iraq in a brief public statement at their Indianapolis church on Monday. Abdul-Rahman Kassig, whose name was Peter before his conversion to Islam, was the fifth European or American captive killed by the militants. His severed head was seen in a video that was released on Sunday and also showed the beheadings of at least 14 men. ...