In the Line of Duty: Street War (1992)

The drug related violence including gang wars in NYC has increased enormously from previous decades. NYPD cop, Raymond Williamson, is shot dead in a staircase in Brooklyn by a cold-blooded crack trafficker. He and his partner, Robert Dayton, swore an oath to look after each other - also after one's death. The detectives investigating the case can't allow him to join them so he does his own investigation.