NYPD whistleblower Frank Serpico, more than a half-century after taking a bullet to the face in a Brooklyn drug raid gone bad, wants prosecutors to take a fresh look at the shooting. The 87-year-old ex-cop told the Daily News he was still seeking definitive answers about exactly what happened inside a narrow apartment building hallway on the night of Feb. 3, 1971. “For years, I didn’t want to believe I was set up,” said Serpico, who feels differently now. “That’s one. And two, I thought ‘How are you going to prove it?’ I want to clear the record for history, what Frank Serpico did and the pric...