So if a murdered successfully kills all the witnesses, he's off the hook as far as you are concerned?
He's not killing all the witnesses unless he commits suicide (I thought you had some kind of law enforcement background)
Understand what our points are.
I'm not claiming forensic science should be ignored.
You appear to be claiming that forensic science should be absolute.
Consider this: Police stop a man running from an alley containing a death by gunshot victim. The runner has powder residue on his hands and the victim's blood on his shoe. The murder weapon is found in the alley and has the runner's fingerprints on it. Should he be executed?