A Manhattan Beach police detective was arrested on suspicion of having raped a woman prisoner. Nigel Starkey, 30, a police officer for five years, was taken into custody while on duty and held in lieu of $20,000 bail after an investigation by fellow officers and district attorney's investigators. Police Chief Ted Mertens said the incident apparently occurred while the woman was in a detention cell at the Manhattan Beach police station Wednesday. She reported it to police Friday, Mertens said. Starkey was booked on suspicion of rape under color of authority and oral copulation while under local detention.