I may be wrong but I think the rules vary by state. It is my understanding, that in Texas, a Justice of the Peace calls for an autopsy in cases of unattended violent death or where a crime is suspected. Neither of those situations applied to Marlise. In this particular case, I think elected officials just want it to fade from everyone's memory.
JMO
What if father decides to sue (for whatever reason). Wouldn't it be better if there was an autopsy? Frankly I am curious as to what exactly was wrong with the fetus. Was it a genetic abnormality precent since conception? That has been suggested by some experts.