Aaron Yoon, a London, Ont., man who went overseas with two high school friends who later perished participating in a militant attack on an Algerian gas plant, has told CBC News he is shocked to hear his friends were killed.

Yoon, who is about 24, was arrested in Mauritania in December 2011 on charges of belonging to an illegal organization. He was sentenced to two years in prison in the summer of 2012.

It appears Yoon had no role in the Algerian gas plant attack by militants linked with al-Qaeda in January of this year, in which his two former classmates, Ali Medlej and Xris Katsiroubas, were among the dozens killed. Yoon was already behind bars in Mauritania when the attack happened.

Before his arrest, Yoon attended a religious school in Mauritania, reportedly with Americans and Europeans, studying the Qur'an. Yoon, was raised a Catholic, but converted to Islam a year before graduating from London South Secondary School. 

Speaking by cellphone with the CBC's Adrienne Arsenault, Yoon said he didn't know Medlej and Katsiroubas had been killed, saying that he lost touch with them about two years ago.

"It's more of a shock to me than it is to you and any other people that know them," he said.

Asked what had happened that led Medlej and Katsiroubas to become associated with militants, Yoon said: " I have no idea. I have been in prison. In reality, I don't really care because I care about my own self.

"I’ve been in prison for a year … almost two years now and I don't see any help from the Canadian government.

"I have been wrongfully accused, I’ve been beat up and tortured. I’m still sick and I still don’t see any medical attention yet," he said.

Yoon said he didn't know why he was arrested and sent to prison, maintaining he had no involvement with militants.

He said he has kept the matter to himself, telling Arsenault he was embarrassed to tell his family and people who know him that he is in a jail in Mauritania. Yoon said he was working up to telling his family what had happened to him.

Gaetan Mootoo, a researcher with Amnesty International, told the CBC's Ian Hanomansing he met with Yoon twice in June and July 2012 when he was charged with belonging to an illegal organization, but prior to his trial.

Speaking via Skype from Paris, Mootoo said Yoon was intially reluctant to speak with him.

"Mr. Yoon … told me he was not interested that Amnesty was keen to work on his case," Mootoo said, adding Yoon instructed him to keep their discussions confidential.

Amnesty International is not campaigning on Yoon's behalf because he asked the organization not to.

The RCMP confirmed Thursday that the remains of Medlej and Katsiroubas were found at the site of the attack on the Algerian gas plant.

CBC News has learned that RCMP in London were asking questions about the three men in June 2012, seven months before the Algeria attack.