Law & Order: Special Victims Unit S02E21 - Scourge

When several people including a child are killed, the team tries to find the killer. They catch the man who did it. Cabot wants to throw the book at him despite his erratic behavior. But Huang wants to examine him and he says that the man is sick. And they eventually learn that the insurance company he applied to knew of his condition and that they didn't tell him which would have allowed him the opportunity to be cured.