Bull crap, you do not need to prove the cause of death, what do you do when there is no body. The kid was missing her sorry ass slut of a mother did not report it. End of case.
Scott Peterson is in prison. His wife and unborn son were found decomposing in water.
He cleaned up the scene of death so good that there was absolutely no evidence of murder.
Yet, an intelligent jury was able to piece together the circumstantial evidence beyond a reasonable doubt and find him guilty of the crime he committed.