Haim reported to be in better shape than previously by friends and was recently talking about abusers.

Both Haim and Breitbart cause of death was Enlarged Heart and both made allegations. (Cardiomyopathy)

Furthermore one of the coroners for Breitbart later died of suspected Arsenic Poisoning.

And finally Both Haim and Breitbart had cause of death signed by the same Deputy Medical Examiner - Juan M Carrillo

Circumstantial of course but worth noting.