An unlikely crime-fighting alliance of an MBTA police officer and a pair of down-and-out panhandlers near South Station foiled an alleged arson-for-hire scheme on Cape Cod and led to the arrest of a Harwich man. Benjamin Parker, 26, was arrested Saturday and charged with attempted arson, conspiracy and possession of an explosive device in an elaborate scheme to pay two homeless men $1,100 to set fire to a single-family home on the Cape. Parker will be arraigned today in Orleans District Court.
