Why did Sam want Jake to witness the act?

In the movie Body Double (1984), directed by Brian De Palma, Sam Bouchard set up the trap for broken down Jake Scully. He gave him a job of house-sitter in a grand house in Hollywood.

Jake Scully witnessed the murder of Gloria Revelle by an Indian (which was later revealed to be Sam). Police had no other option than to pressurise Jake for confession and they were doing nothing in the case. Jake tried hard and finally found that Sam set him up. In a phone call to the police officer Jake quotes

He wanted me to witness the murder, Sam Bouchard was Alexander Revelle.

(Sorry for not quoting the actaul dialogue, but he did say something like that).

Now, my question is why Sam wanted Jake to witness the murder. How would it have helped Sam in not being suspected? We may or may not know why Sam killed Gloria but I think we can know why he wanted Jake to witness his brutal acts.

plot-explanation body-double

Best Answer

He (Alexander) wanted Jake to witness the murder in order to distract from him as the suspect. If he would just have killed his wife without anyone seeing it, he could easily be a suspect in it. But since there was someone who saw the murder and who swears it was an Indian, it at best steers the suspicion away from Revelle and at least it might cause some confusion in the investigation. Someone else who doesn't look like you at all killing your wife is better than someone unknown who might just be you.

I also don't quite remember if Revelle also prepared himself an alibi (by whatever means), in which case it's also useful to have the exact time of the murder on record, to further drive suspicion away from him. Preparing an alibi ony pays off if you actually need it.

However, I agree that this isn't quite as well thought-through as the film might want to make us believe. There would have been many ways in which this setup could have blown, either by the police investigating further who actually gave Jake his house-sitting job or by Jake seeing Revelle at some point during his tasks as a witness (though, they certainly wouldn't ever have captured the "Indian" anyway). So it might not have been as clever a plan as Revelle had thought (and ultimately didn't work out), but that is very much the reason to set up Jake as a witness, to disturb the investigation and direct suspicion away from Revelle.