Investigation Discovery

She had confessed to planning the murder of her mother and her mother's husband. When detectives said she was going to jail, her first concern was herself, a reaction an expert calls an extraordinary lack of empathy.

Watch "Signs Of A Psychopath" Tuesdays on ID and stream on @HBOMax.

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Living in her parents' home, a young couple talked about a quieter way to kill: sleeping pills in every drink. An expert says the real motive was getting rid of two people they found inconvenient, and calls the plan calculated and premeditated.

Watch "Signs Of A Psychopath" Tuesdays on ID and stream on @HBOMax.

#SignsOfAPsychopath

Investigators believe Danita Brown went to Bob's apartment hoping to get money for the trip home to New Gloucester. According to their account, Bob stepped away to the bathroom, and when he came back, he found her going through his wallet.

Watch "A Body in the Basement" on ID and stream on @HBOMax.

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One man describes going down into a basement with no real lights, across uneven ground covered in boards and debris. Once he was inside, nothing he saw immediately suggested a body was there.

Watch "A Body in the Basement" on ID and stream on @HBOMax.

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Detectives tell him a jury could see either a cold-blooded killer or someone acting in self-defense. He says the man got angry and tried to attack him, insists he didn't mean to stab him, then admits he "just saw red and kept going."

Watch "Signs Of A Psychopath" Tuesdays on ID and stream on @HBOMax.

#SignsOfAPsychopath