The Canadian Security Intelligence Service is looking for another young man from London, Ont., who may be connected to Canadians involved in a deadly gas plant attack in Algeria, CTV News has confirmed.

Mujahid Enderi, who also uses the first name Ryan, is believed to have travelled overseas at the same time as three other young men from London – Ali Medlej, Xristos Katsiroubas and Aaron Yoon.

The RCMP confirmed last week that Medlej and Katsiroubas died in the January attack on a remote gas plant in Algeria, which ended with the deaths of 37 hostages and 29 terrorists.

Medlej and Katsiroubas are believed to have been part of the militant group that carried out the attack.

Their high-school friend, Aaron Yoon, is currently serving a two-year jail sentence in Mauritania for alleged ties to al Qaeda. Yoon travelled with them overseas but did not go to Algeria.

Now, Canadian authorities are trying to locate Enderi, who dropped off the radar last year.

Enderi went to the same London high school as Medlej, Katsiroubas and Yoon, but was a few grades behind them, according to The Canadian Press.

Enderi’s younger brother, who still lives at the family home in London, told CP that Enderi was “definitely not” involved in the Algeria attack.

But Ubada Enderi refused to elaborate or discuss his brother in detail.

Neighbours said the Enderi family included two sons and a daughter, who seemed to run free in the neighbourhood when their father was not home.

RCMP Commissioner Bob Paulson wouldn’t say anything about the latest revelation, but said the Mounties are still investigating Canadian ties to the Algeria attack.

"It is a little frustrating because I don't think people fully understand the phenomenon of home-grown radicalization," he said.

"It's something I think we need to get serious about. We need to co-ordinate our efforts in our communities and make sure we're able to prevent these things.”

With files from The Canadian Press