Another spoiler
The veterinarian walks in on a "suicide" but could not figure out that the poison may have been in the flask that was sitting right there?
shareI didn't have a problem with that.
Doc was suspicious about Janet, so it's doubtful he believed her when she said suicide. Especially since the guy was lying there with his overcoat on. Who puts on a coat to kill himself, indoors?
Janet's story would have fallen apart anyway -- the key around her neck, the jeep with no brakes, and doc basically knowing everything from the beginning.
Nifty little cat and mouse movie.