Accidental death life insurance question?

My friend’s Father recently passed away and had life insurance. My friend now thinks he will be getting a huge check from the insurance company, but I’m not so sure. His policy was for accidental death or dismemberment but he died of natural causes. Does anyone know if “natural causes” would be considered accidental? Also, he had just found out recently that he had inoperable cancer - so I’m not so sure how natural those natural causes actually were - my friend thinks he may have od’d on purpose. The death certificate did list natural causes though.