The RCMP say the man who ran over two soldiers before being killed by police on Monday had been under investigation since June.

The Mounties say they began investigating Martin Couture-Rouleau in June after he began posting remarks on Facebook that indicated he had become radicalized. They detained him in July when he tried to leave the country and confiscated his passport. But they couldn’t arrest him because radical thoughts are not a crime.

Couture-Rouleau had converted to Islam and a Twitter feed believe to be his showed the banner of the violent terrorist Islamic State.

RCMP say they had reached out to Couture-Rouleau’s parents, and the Imam of his mosque, to get them to convince him to give up his radical beliefs. He was one of 90 Canadians under surveillance by the federal force for supporting Islamic State.

Couture-Rouleau was killed by police following a high-speed chase after he ran down two soldiers with his car. One of the soldiers, 53-year-old Warrant Officer Patrice Vincent, died of his injuries.