You don't need to.
Bodily trauma kills.
I've shot enough people to see that effect first hand.
Also the viruses demonstrated in their experience didn't prevent carrier death through torso shot.
So what? Dead in our world is not "dead" in Resident Evil, especially for Umbrella. Viruses capable of reanimation, among other things, had already been created by the time Spencer was assassinated.
This literally carries no weight as a point of argument considering Mr X, far more durable then a person, just as dead after a few seconds of machine gun fire.
Compare this to multiple other T-103's who do not die from a few seconds of machine gun fire, or even Lisa Trevor who was around during the experiments at the Arklay facility... Or Birkin.
Hell disposal of body is a better point if not by much.
Because again.
How the hell is a leech assuming his mind even a predictable outcome?
I never said it was predictable, but it was easily preventable. Even if it wasn't predictable, Umbrella must expect that such disastrous and seemingly unprecedented events can and will occur when employees forgo totally basic safety procedures.
Actually, maybe it wasn't so unpredictable, because the mutant leech he was working on, the same one they didn't bother to secure, is of the same pool of subjects Marcus used to create the Progenitor virus, and later the T-Virus. Reanimation is entirely feasible by this point.
Also I'll have to disagree on the raccoon point considering all the key players were there directly because of Marcus.
You mean Umbrella. Even if all the key players were in place because of Marcus, Umbrella once again flubbing an assassination of its own staff leads to the release of both the T and G viruses.