That's the problem. Been about a dozen of these coma cases here in the last year. They're...

Jim:

First rule of crime: Keep It Simple. What's simple? Carbon Monoxide. Pathology Resident #2:
Boring. Dr. Susan Wheeler:
Carbon Monoxide? Jim:
Sure, it's perfect. Anesthetist feeds the patient some carbon monoxide instead of oxygen. It's colorless and makes the blood very red so the surgeon doesn't notice anything funny. But the brain dies from lack of oxygen. End of operation - the patient doesn't wake up. Dr. Susan Wheeler:
No other effects? Pathology Resident #2:
Sure, other effects. Cardiac irritability. Jim:
Which this case had. Pathology Resident #2:
You know, it'd be much better to block the neuro-muscular junction with succinylcholine. Now that's a nice murder. Jim:
Yeah, who's gonna do it? Pathology Resident #2:
Well, who's gonna feed you Carbon Monoxide? Jim:
That's the problem. Been about a dozen of these coma cases here in the last year. They're always different. Different case, different anesthetist, different operation. Hard to imagine it's murder