In April 2005, Stephen Stanko murdered his girlfriend Laura Ling, and then raped and stabbed her daughter. Shortly afterwards, he killed a friend, Henry Turner. At his trial for Laura's murder, Stephen's lawyer called on medical experts who claimed that PET scan images of his brain revealed that he was born with a brain defect that made him psychopathic and, on occasion, temporarily insane. “48 Hours" correspondent Troy Roberts reports. This classic "48 Hours" episode last aired on 9/1/2007. Watch all-new episodes of “48 Hours” on Saturdays, and stream on demand on Paramount+.

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