Blackout (S04E13)

Lilly investigates the 1996 murder of a wealthy divorced woman who was found dead in her ex-husband's indoor swimming pool. The original investigation ruled the death accidental, but new evidence suggests it was a homicide. It's also learned that the victim died during a citywide blackout and that she was terrified of the dark. In addition, the victim was a bitter woman and hated by most of her family members. (CBS TV Network)