In the morning , the authorities come for the dead bodies , as the girls had apparently made a suicide pact : Bonnie hanged herself , Therese overdosed on sleeping pills .
Lux died of carbon monoxide poisoning after sealing herself in the garage with the car running .
In the morning , the authorities come for the dead bodies , as the girls had apparently made a suicide pact : Bonnie hanged herself , Therese overdosed on sleeping pills , and Lux died of carbon monoxide poisoning after sealing herself in the garage with the car running .