What we do know for certain is that somebody is lying because 25mg is not a lethal does its much less than the recommended dosage of 1-2.5mg/kg , if we consider Michaels weight. The low dose may have been due to Murray pumping Michael full of benzodiazepines before administering the propofol. As i said in a previous post, toxicology results are of limited value in this circumstance as they do not always show a lethal level of propofol at autopsy. The crime scene probably offers better evidence as there are likely to be discarded vials of propofol left behind or in this case just ask the doc.