Police believe two members of the Crips killed an off-duty corrections officer yesterday morning in order to steal his motorcycle. Kenneth Duncan, who had worked for the city's correction department for 17 years, was found shot in the head outside his Remsen Village home. According to a police source, the men approached Duncan and a friend in Duncan's garage as they were installing new exhaust pipes to his Kawasaki Ninja ZX-14 motorcycle. Duncan is described......