Stephen Foster, 44, was found guilty on Thursday of breaking into the Civic jewellery store in late 2013 and stealing goods worth $34,244 from the shelves.

CCTV vision clearly showed Foster repeatedly returning to the store over two nights, before eventually gaining entry to the store's display area.

His fingerprints were found inside and police noticed scratch marks on the door's lock.

Foster had protested his innocence to the crime, claiming he had been contacted by the owner of the store, Gems and Gems Jewellery, through a mutual friend to stage an insurance job.

He claimed the business was failing, and that he'd been promised $500 for the "pretend" burglary. He apparently told his friend to "line it up" for November 27, 2013.

But Foster said he didn't go to Gems and Gems until two days later, walking in through "unlocked" doors.

He said he felt ripped off when he discovered only $200 had been left for him, and grabbed jewellery to sell later.

The next night, he claimed to have gone back to the store, and saw the owner replacing the stolen goods on the shelves.

Foster said he waited until the worker left, walked back in, again through locked doors, and found more cash and took more jewellery.

He said he went to a Fyshwick brothel to sell some of the loot for drug money.

It was a story that ACT Supreme Court Justice John Burns described as "utterly implausible" when finding Foster guilty on Wednesday.

"It is implausible that the owner would have left the doors to the display room unlocked on both Friday 29 November 2013 and Saturday 30 November 2013 if the accused had not attended as planned on 27 November 2013, and no other arrangements had been made," he wrote.

"In addition, if, as the accused asserted, he had conducted the pretend burglary on Friday 29 November 2013, why would the owner have entered the store on Saturday 30 November 2013 and replaced the items which the accused had removed?

"That simply makes no sense."

Justice Burns questioned how Foster could possibly have known what the owner looked like when he went back to the store on the second night, when he himself said the pair had never met.

He accepted the evidence of the store owner, who said his business was doing fine.

The amount the store was insured for had dramatically reduced prior to the burglary, something inconsistent with a fraud job.

Justice Burns also found the owner could not possibly have made money in the arrangement Foster claimed to have existed.

"Even if the accused's estimate of the value of the goods that he took ($2500.00) is correct, [the store owner] still lost money on the arrangement," he said.

"All of this appears implausible."

He found Foster guilty on two counts.

Sentencing will take place at a later date.