Dr Charles is asked to help Intelligence with a diagnosis of a doctor who has been overdosing his patients with chemotherapy. A case for him being a psychopath can get this doctor convicted.

Season 3 Episode 10 "Now I'm God"
The case of cancer-free patients being overdosed on chemotherapy takes a dramatic turn when it is revealed that the doctor responsible treated the late wife of Voight. Distraught over this, Voight does everything he can to convict him. Meanwhile, Burgess investigates an incident that got Roman suspended.

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