Met Police officer Ben Hannam has been convicted of membership of the banned neo-Nazi group.
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Ben Hannam was asked if he had ever been in the far-right British National Party or any organisations whose aims "may contradict the duty to promote race equality" on his application form to join the Metropolitan Police in 2017.
He ticked "no" and got accepted.
He then spent two years in the force, working with communities in north London and interviewing his own suspects.
He appeared in a neo-Nazi propaganda video just two days before he applied to join the force.
Hannam claimed "there are no pictures of me doing a Nazi salute" during his trial, but the BBC has identified him at a fight training event, filmed for a National Action propaganda video, which he arranged to attend in August 2016.
One of his old school teachers told the trial she had been unable to mark one essay submitted by Hannam - the first time this had happened in 20 years of teaching - because of "concerning content" and his "intolerance" towards Islam.
He was also spoken to after students at his diverse school reacted to "anti-immigration" views he espoused during a debate.
The Met never took a reference from the school.
After he was charged, three experts agreed Hannam was autistic and that this was relevant to his interest in fascism, an ideology historically associated with order and structure.
One said Hannam was well aware of what National Action stood for. The others said his autism meant it took him some time to realise the group was "morally bad".
Prosecutors said his diagnosis did not excuse his conduct or explain why he sought friends in a neo-Nazi group.
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