Jason converted to Islam at 16 (some sources say 13) and later adopted the name Abu Mujahied Amrik. His talk about jihad against the non-believers caused his mosque to ban him and his brother and notify the authorities. His mother, recently divorced, and with two younger daughters at home, felt increasingly unsafe finally fleeing to a woman's shelter.
Jason has made at least one visit to Pakistan and possibly to Afghanistan where it is alleged he has received training at a terrorist training camp. Jason was arrested along with Ismail Akhnikh on 10 November 2004 after a massive 14 hour siege in The Hague. Near the end of this siege, hand grenades were thrown at police. This was one of a series of raids on suspected Muslim terrorist cells following the 2 November 2004 assassination of filmmaker Theo van Gogh by fellow Hofstad Network member Mohammed Bouyeri.
According to police, Walters had his own plans to assassinate Dutch political figures he deemed anti-Muslim, and his hit list included two members of parliament, Ayaan Hirsi Ali, a native of Somalia, and Geert Wilders. Both, like van Gogh, had been outspoken critics of Islam in the Netherlands, particularly its treatment of women. In 2003, Walters wrote a farewell letter to his mother.