Didn't Deserve to Die
In most episodes, the murder victim had a checkered history (blackmailer, extortionist, embezzler, even a murderer), deserving of some retribution.
Name an example or two of a victim who was relatively blameless.
In The Case of the Angry Astronaut, James Coburn played a cool, efficient head of a space program, sort of a Derek Flint without the charm. He was murdered but not for any nefarious conduct on his part. (He washed out the Angry Astronaut from the program, but at the end the astronaut grounded himself, vindicating Coburn's action).