07/26/2013 03:53 EDT | Updated 09/25/2013 05:12 EDT

Canadian man convicted of al-Qaida ties in North Africa returns to Canada

OTTAWA - A London, Ont., man jailed in North Africa for his alleged links to a terrorist group has returned to Canada, with questions hanging over him that may never be answered.

A federal government source said Aaron Yoon arrived Friday in Toronto.

Yoon was arrested in Mauritania in December 2011 and sentenced to prison after being convicted of having ties to an al-Qaida-affiliated group.

Police and terrorism experts may want to ask Yoon what he knew about a deadly act of terrorism that killed his former London classmates in Algeria last January.

There are also questions about how Yoon and schoolmates Ali Medlej and Xristos Katsiroubas were allegedly radicalized, and by whom.

Medlej and Katsiroubas were killed in an al-Qaida-linked terrorist attack on an Algerian gas plant that killed 39 hostages.

It's uncertain whether Yoon will speak about those matters, or whether he is even obligated to do so. His family indicated to media in London on Thursday they would not talk.

And calls to the Yoon family home by The Canadian Press on Friday were not returned.

Yoon was in prison when the attack occurred in Algeria, his two-year sentence was later reduced, allowing him to be released earlier this week.

The RCMP would not say whether Yoon was escorted by any of their officers on his flight back to Canada.

Yoon has said he travelled to Mauritania in May 2011 to study Arabic and Islam, and has denied having any ties to terrorism.

He has also told Amnesty International he was tortured by his captors while in prison.