Why should a criminal be more cautious than a theatre medic?

Why should criminals scrub up and scrub down more carefully? Medics may be at risk of infecting patients (Golden Staph) or spreading infections from patients (Ebolla) — but usually not both with the same patient. For every crime, the criminal may leave evidence at the crime scene and take evidence away, according to Locard’s Exchange Principle. Theoretically at least, a criminal’s attire and interactions could require more caution.
In my political crime fiction novel Presumed Dead criminals run the Locard’s gauntlet.

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