Many conmen get their victims to lie, either by forcing them to lie, or creating a reality the victim thinks is true.
They often use fear tactics to get them to act, such as saying HE is in danger or their VICTIM is in danger.
The Tinder Swindler (Simon Leviev) told his victims he had enemies who were after him and even showed them a video of himself in an ambulance all beaten up after an supposed encounter, so he couldn't use his bank card for fear of being traced, so his victims gave him theirs and lied to banks to get more money for him.
The Puppet Master (Robert Hendy-Freegard) conned a group of uni students into believing their lives were in extreme danger from terrorists and that he was protecting them as an M15 agent. He dragged them around the UK for a decade, giving them aliases and new lives. Even letting them see and speak to their families while they told giant fibs they thought were true and lies he forced them to tell.
Then there's the French con artist (Thierry Tilly) who used fear mongering to cause an aristocratic family to lock themselves away for a decade, fearing their lives were in danger if they stepped outside the house.
We don't know how he coerced Marion. There must have been a good reason she changed her name in secret. Remember that before Marion left, she told a friend 'if something happens to me look after Sally and Owen'. And the fact she was uneasy letting her kids see the man she was meeting up with, and obviously knew for months.
We've only heard from two witnesses. JO seems so sweet and trusting he never had to force her to do anything! But GGB was more reluctant and he took naked photos of her and tried to blackmail her and reported her to her employer! Other witnesses may be able to testify to his fear tactics.
The more relevant question is... did Marion have a history of lying before meeting him?
