Do any of you know what happens when someone overdoses and dies from a methadone overdose?How long rigamortis?

My babies father was found, in the bathroom, stiff, with black vomit on his lips and hair, and the impression of a toilet seat on his chest. Also his pants were down. He was hospitalized over night on Thurs. because he stopped breathing from methadone, released and found dead 4 days later.

: http://alcoholdrugstreatment.info/do-any-of-you-know-what-happens-when-someone-overdoses-and-dies-from-a-methadone-overdosehow-long-rigamortis