A photo of Byron Sonne from the social networking site Facebook.

A Toronto man has been charged with explosives and weapons offences in what police are calling a G20-related arrest.

Police searched a house at 58 Elderwood Dr., in Toronto's upscale Forest Hill neighbourhood, just after noon on Tuesday.

Byron Sonne, 37, was charged with:

• Possession of explosives for an unlawful purpose.
• Possession of dangerous weapons.
• Intimidation of a justice system participant by threat.
• Intimidation of a justice system participant by watch and beset.
• Mischief.
• Attempted mischief.

Sonne appeared in court Wednesday afternoon, but the details are subject to a publication ban. He is scheduled to appear in court again Saturday afternoon.

Sonne likely testing security, say friends

Police have released few details about the case.

But Robert Beggs, who knows Sonne, told CBC News that Sonne was a member of a group called the Toronto Area Security Klatch, a group of security professionals who share knowledge and research on matters related to IT security.

The group meets monthly, and Beggs told CBC News that Sonne has made presentations to the group on several occasions.

Beggs described Sonne as an independent online security specialist. Beggs also said he believes Sonne is a licensed private investigator.

University of Toronto professor Andrew Clement met Sonne at a recent meeting of computer experts interested in what he calls probing surveillance techniques.

Clement said he believes Sonne may have been trying to test police security measures in advance of the G20 meetings in Toronto this weekend.

He said Sonne talked about listening to police radio transmissions during the summit.

"But I didn't understand that there was anything illegal about that or that he was going to do anything sort of extraordinary in those measures," Clement said.

Friends say Sonne had talked about sending messages with trigger words or buying up fertilizer during the summit to test security measures.

Friends and neighbours said the idea that Sonne was involved with any explosives or weapons is out of character.

Sonne owns and operates a business called Halvdan Solutions, which he registered on Nov. 28, 2008. He is the sole owner and it deals in computer and info technology services and solutions.

The Forest Hill house remained cordoned off Wednesday and a number of specialty police squads, including the emergency task force and the bomb squad, have been working at the house.