Reluctant Heroes - S4.E8

Coming home from the movies, MacLeod and Richie witness a murder attempt on grocer David Markum. MacLeod saves Markum, but Markum's wife Alice is hit and killed. MacLeod and Richie go after the murderer and discover he's Immortal Paul Kinman just as the police arrive and arrest him. MacLeod wants Kinman's head. Kinman killed MacLeod's good friend Dennis Keating when they were in the court of Queen Anne. FBI agent Kaayla Brooks asks MacLeod and Richie if they can testify against Kinman, but MacLeod refuses because he can't kill Kinman if Kinman's in jail.