A New York Police sergeant admitted yesterday that he illegally used a city police computer to get registration information on two cars as a favor for a Long Island crack dealer. The cars were being used by DEA agents for surveillance on the dealer, Frank Wilson, who gave sergeant Roosevelt Green a pair of sneakers worth $20 and a discount on several other pairs in exchange for the information. Green, an 11-year police veteran, confessed to the misconduct and lying to DEA investigators when they questioned him about his relationship with Wilson. But Green's lawyer insists his client was unaware that Wilson was a drug dealer, telling Newsday that Wilson said he wanted the car ownership information because he suspected robbers were following him. Fortunately, the ownership information was false, to prevent the cars from being traced back to law enforcement. Green faces up to 5 years in prison and has agreed to quit the city police force. It's unclear if he gets to keep the sneakers.