Why did Edgar J Hoover allow Marilyn Monroe to die?

Now this has probably deeper roots, but the input of all and sundry is welcome. One of the reasons would be his hatred of Bobby as well disrespect of JFK and their dad, tied in with anti catholic, prohibition era stuff etc. Then add to that his connections in and over the establishment, and whatever did happen to his safe with all the info that got burgled when he died, theres no way it was destroyed, it would have been kept and used(except for the info relating to the takers and their sponsors.

Please add scenarios and info and lets see what we come up with.