A man charged with possessing explosives ahead of last year's violence-marred G20 summit appeared incredulous Monday when photographs of chemicals and other items seized from his house were shown in court.

The items were found in the basement of Byron Sonne's home as police executed a search warrant days before the summit in June 2010.

"They can make anything look nefarious," Sonne said as court recessed.

Among the items were numerous containers of chemicals with ominous-sounding names like hexachloroethane, tetrahydrofuron and methyl hydrate.

There were also components from a microwave oven labelled magnetron and other electronics.

When Crown witness Det. Const. Irvin Albrecht described a piece of garden hose attached to an air compressor as an item of interest because "it didn't make sense," Sonne spun around in court and flashed an incredulous grin.

He later said outside the courtroom the item was for cleaning his garden irrigation system.

One item Albrecht initially labelled as a home-made detonator turned out to be part of a temperature sensor.

Sonne, who is charged with possession of explosives and counselling mischief "not committed," was arrested on June 22, 2010, as he rode a city bus.

The trial proper began Monday morning after Ontario Superior Court Justice Nancy Spies ruled that search warrants for Sonne's home were based on "credible and reliable" evidence.

She also said several statements Sonne made to police were voluntary and therefore admissible.

The defence had wanted the material excluded as a violation of his charter rights.

With those rulings, Sonne's trial kicked off with an agreed statement of facts that included his purchase of chemicals.

The 39-year-old self-described security geek was seen taking photographs of the security fence that was being erected on June 15, 2010, about two weeks before the summit began, according to the agreed facts.

He had a camera and police scanner with him, court heard.

Police allege he assembled chemicals for homemade explosives and incited others to tear down the G20 security fence and surveillance cameras through his Twitter and Flickr accounts.

Among its witnesses, the Crown plans to call Crawford Anderson, a military expert in organic chemistry and improvised explosive devices, prosecutor Liz Nadeau told court.

The Crown is not alleging he was going to blow anything up at the summit.

"We don't know what he was planning to do with the explosives," Nadeau said during a break.

"We do know there was a fascination with the G20."

Sonne has always maintained the chemicals were legal, were not combined in a dangerous way, and were actually used for making model rockets and crystals.

Supporters also say he had been trying to expose flaws in G20 security — which cost hundreds of millions of dollars — and was quite public in the way that he did so.

Court heard that Sonne, who joined a model-rocket club, bought chemicals such as zinc oxide and five plastic jars. He also bought potassium permanganate, which required a licence.

One of his suppliers turned out to be someone also used by Toronto police.

Court heard a rifle scope ordered from the United States was seized at the border although pellet-gun oil in the shipment was allowed through.

Other items found in his home included various electronic components, an audio-level meter, camping heater fuel and homemade electro-chemical contraptions.

Police found no books on bomb making, but did turn up the "Encyclopedia of Serial Killers."

Sonne spent 330 days in jail — longer than any of the other more than 1,000 people arrested in connection to the summit — before being released from custody in May.

Before his arrest he lived in a million-dollar home in Toronto's Forest Hills neighbourhood and was married to Kristen Peterson, an independently wealthy artist.

She was also arrested, but charges against her were dropped.

Now he's in the middle of divorce proceedings and living with his parents.

The trial continues Tuesday with Albrecht under cross-examination.