T. J. Hooker - Season 5 Episode 3 To Kill a Cop

After an off-duty Officer is shot dead in a grocery store, Hooker – an old friend of the family's – promises the dead man's wife and son to find the culprit. A case in which the deceased Officer's partner sent a criminal to prison on a false testimony may be the key to the killing; but all the time, the killer has his next target in his sights... Meanwhile, Hooker looks into the recent murder of a local prostitute, only to discover that the two cases are linked.