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Folie à deux is a French term that means ‘madness of two’. It can also refer to a shared psychosis or a shared delusional disorder.

In 2008, identical twins Ursula and Sabina Eriksson were acting erratically. They had traveled to England from Sabina’s home in Ireland. The sisters were asked to leave a bus that they had been traveling on as they were acting paranoid and would not let the driver search their belongings. After they got off the bus, the sisters ran into oncoming traffic on a motorway.

Ursula would be hospitalized for months, while Sabina was released soon after the event. Sabina would wander the streets of Stoke on Trent in England, looking for her sister. A man named Glenn Hollinshead took pity on Sabina and took her in. Sabina would end up killing Glenn by stabbing him five times with a kitchen knife. Neither sister has given any reason for their actions.

We also discuss the strange case of the Tromp Family. In 2016, Mark and Jacoba Tromp fled their home in Silvan, Australia, along with their three adult children Ella, Mitchell and Riana. The family were convinced that people were after them and that they were being tracked by their devices.

One investigating police officer described this case as "the most bizarre case I've seen in 30 years".

The family would all eventually be recovered safely, following a large-scale police investigation. Mitchell Tromp would later say 'I've never seen anything like it. It's really hard to explain or put a word on it but they were just fearing for their lives and then they decided to flee. It was a build-up of different, normal, everyday events - just pressure - and it slowly got worse as the days went by."

Read our blog for these cases - https://truecrimesocietyblog.com/2026/02/24/folie-a-deux-crimes-events-of-shared-psychosis/

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Folie À Deux Cases / Shared Madness | Ursula and Sabina Eriksson & The Tromp Family