Hmm. It's possible, given that the handful suicide cases I've found where autopsies weren't performed were cases in which the cause of death and intent to commit suicide were so blindingly obvious that an autopsy would just be a waste. (And, in many of them, a family remember requested that an autopsy not be performed.)

The bottom line is, I don't know much about the relevant laws or how medical supervision affects things. To get a definitive answer, you'd probably need to contact a cryonics provider, a doctor, or a lawyer.