Well the other night I pulled this episode off the shelf and took a look at it. Yes I still have an old VCR with the original Colombo series on tape.
To this day I never understood why Abigail Mitchell gave Columbo those **** keys. Stating that you are the keys but I did not kill Edmund. Why couldn't she just put them away in her pocket or drop them over this side of the pier quickly before Columbo got too close to her. He certainly was not going to say to her what did you just put in your pocket? And then to make up an excuse like they were out back next to a sprinkler later on? And this is coming from a woman who writes about murder and configure the most Sinister plots? This was a rookie mistake. Never understood it
Maybe she felt like she couldn't hide them inside any longer because she was vulnerable to a Search Warrant.
And maybe she felt like she was always being watched outside too, by someone she had not met.
Bottom line is that she didn't feel there was any real evidence on which to hang a conviction. She decided that her best play was to give Columbo what he was determined to find, so that she wouldn't be caught trying to hide them or dispose of them, which would be self-incriminating.
There are several other suspects, such as Ward Fowler in Fade in to Murder, and even way back to Dr. Ray Fleming in Prescription Murder, that pretty much dare Columbo to find some incriminating evidence.
She screwed up in the beginning by trying to write the script for the murder and blurted out that it was an accident... Columbo's response puts her on the ropes; the rest of the episode is good entertainment though.