As if the guinea pig was even necessary. She was doomed the minute she hit the investigator. Her files and the reports she'd submitted up to that point would be a paper trail leading right to the murderer. On top of that the episode also just completely forgot about the hotel clerk another witness who could lead the cops right to the killer. Crocodile tries to be one of those "It was the perfect murder, except for one mistake!" type stories but actually it was dozens of mistakes. There was no way she would get away with it.

In fact the guinea pig was the last thing that should have done her in. Those things have terrible eyesight, it wouldn't have seen crap.