I am leaning towards an accidental OD. FWIW, I watched a documentary on Netflix that discussed a psychiatrist whom she dealt with in the last while of her life and he went away to Europe during that crucial period (in about late June, no later than early July 1962). The theory postulated is that Marilyn was likely that more vulnerable during that period without that person’s immediate counsel and help and she likely overdosed during a “bad” period.
“I am leaning towards an accidental OD”
We will never know—they covered it up in a hurry.
It is kinda the Bobby version of Chappaquidick—regardless of whether he was responsible for her death he almost certainly had an opportunity to try to save her and instead fled the scene.