I just watched "Negative Reaction" for the umpteenth time (this is one of the 2 best episodes IMHO). Each time I see something new. The writers and directors really put a lot effort into little things that it is easy to miss. Two examples:
(1) During Frances Galesko's funeral, the camera first focuses on the casket and then pans to the chief mourners who are sitting in a row, first Paul Galesko, then an unnamed woman, and then Miss McGrath (Galesko's assistant and "love interest"). While the camera is panning we hear the minister speaking. He says (I don't recall the exact words) something like "all who come into the world must pass out, the guilty (right at this point Paul Galesko pops into view in the camera's panning) and the innocent (right at this point Miss McGrath appears)". This is really beautiful!
(2) In the final showdown when Galesko is summoned to Columbo, as he enters the room where Columbo is waiting for him, there is a wire screen between Galesko and the camera, so we see the screen partly obscuring him. My daughter who studied video production tells me that this is a hint that Galesko is going to soon be behind bars! This type of shot is also used to show that something bad is going to happen to the character being shown.
We should keep our eyes open for these type of seemingly small things-this is why we can watch these programs over and over, knowing what is going to happen, and yet continue to enjoy them!

These are excellent observations. My other favorite example of this type is the scene in which Dr. Collier prepares to hypnotize Nadia Donner to leap to her death. He is photographed in the frame with the fireplace flames licking all around his head...because what he is doing is purely evil.

Something similar is seen in the beginning of "Publish or Perish". Professional bomb-maker Eddie Kane is practicing throwing them and he has a fire burning in front of him to like the fuses. Riley Greenleaf (Jack Cassidy) shows up to talk to him and the camera looks at Greenleaf through the flames of the fire.

Another little thing about a year after "Negative Reaction." It was in "Forgotten Lady." Grace Wheeler (Janet Leigh) asks Columbo if he has taken leave of his senses. Very ironic, considering the nature of the ending.

And when Columbo enters the real estate office post homicide in RIP, Mrs. Columbo, Mrs. Dimitri says something like "Things are a little crazy here right now".

Joe

It's interesting that you mention the "Miss McGrath" character, because apart from Frances' suspicions, the story never really tells you that there was anything between her and Paul. So if you consider adultery a sin, she might have been as innocent of that as of murder. I always notice that as she's walking away in that scene, she observes "custom" by not stepping directly on the front of a grave, sidestepping it instead. I always wonder whether that was planned, or just reflex on the actress' part.