Nobody ever showed there was no blood on his hands. After being exposed to the rain for some amount of time the examiners didn't notice any visually, and that was it. There was never a test that showed none was there.
The ME even said that if he didn't visually see anything amiss, no tests were conducted. He did not spend a lot of time with his autopsies.
How many times did he say something was not his job and that he had "on confidence" with the people he supervised...