Murderer Chris Watts forced a Tinder date to play out a 'rape fantasy' just months before slaughtering his pregnant wife and two young daughters in August 2018, police documents show.
Watts met Amanda McMahon at a Chick-fil-A restaurant earlier in 2018 after chatting to her on the dating app, Knewz.com reported.
McMahon said she had only met up with Watts, 35, for a 'one-time thing' but that the future family annihilator became 'really fast and aggressive' with her during sex.
She told police that she had to physically fight Watts off of her after he turned violent, putting his hands around her throat and trying to initiate anal sex despite McMahon's reluctance.
He also revealed details of his 'rape fantasy' to her in extreme detail.
Amanda McMahon (left) who claims she had an affair with Chris Watts (right) said she met him on Tinder and on their first date they watched Shutter Island, a movie that may have inspired the Colorado killer's lies
In earlier reports, McMahon said she and Watts had also watched Martin Scorsese's film Shutter Island during their meeting.
In the film, a man kills his wife after she murders their children - Watts would later attempt to use a similar storyline when explaining his family's murders to police.
Watt's sex life in the months leading up to his crime has been a subject of much speculation, with several people coming forward claiming to have been involved with the married father of two.
A former male sex worker has said that he and Watt's had a 10-month affair. Trent Bolte claimed the two spent time together in a remote Wyoming cabin.
Watts has denied this, saying: 'That blew my mind. I was like, "Who the hell is this guy?"
The convicted murderer has also denied McMahon's account of his 'rape fantasy'.
Watts killed his wife Shanann, 34, and their two young daughters Bella and Celeste in August 2018. Shanann was pregnant at the time of her murder
The killer dad initially blamed the girls' deaths on Shanann, saying he'd killed her in a fit of rage after she murdered their daughters. He later admitted to carrying out all three murders himself
In five hours of released police interviews, Watts denied having any extramarital affairs except one with his coworker Nichol Kessinger.
It reportedly began when Watt's wife Shanann, 34, and their two daughters Bella and Celeste spent the summer of 2018 in North Carolina with her family.
Watts stayed home in Colorado