Former parliamentary Speaker Peter Slipper could face jail after being found guilty of dishonestly using his travel entitlements to visit vineyards.

Peter Slipper will have a nervous two-month wait before learning whether he’s going to jail for dishonestly using taxpayer-funded cab charges to tour Canberra’s wine district.

The former parliamentary Speaker was found guilty on Monday of three counts of dishonesty and could face up to a year in prison or $10,000 in fines when he’s sentenced on September 22.

Slipper remained impassive as the verdict was read out and said nothing to journalists as he left the court.

The former Queensland MP had admitted using his government travel entitlements to visit the vineyards outside Canberra on three separate occasions in 2010 but always denied he acted dishonestly.

ACT Chief Magistrate Lorraine Walker disagreed, concluding there was only one reason he didn’t write down his true destination when filling out the $900 worth of travel vouchers used to fund his trips.

“That was to misrepresent what he had actually been doing,” she told the ACT Magistrates Court on Monday.

Slipper tried three times to have the case dismissed, including once on the grounds of mental illness. But Magistrate Walker ruled the trial should go ahead in the public interest.

The prosecution argued Slipper manually filled out multiple vouchers for single journeys in an attempt to hide the non-parliamentary nature of the trips.

MPs and senators can only use taxpayer funds to pay for official or parliamentary business and the prosecution claimed Slipper knew he was breaking the rules.

Slipper was accompanied by a male staffer on two of the trips and his wife – also on his staff – on one occasion.

On handing down her decision, Magistrate Walker said it wasn’t unusual for Slipper to fill out multiple cab charges by hand instead of paying electronically.

But she said his decision to fill out the destinations as “parliament to suburbs” and “suburbs to suburbs” when he was knowingly visiting vineyards well outside Canberra was implausible and dishonest.

“The contents of these vouchers is clearly false,” she said.

Slipper’s legal team said whether the government incurred any financial loss from their client’s actions was in dispute, as were his intentions.

The court was previously told Slipper’s life had spiralled into despair as a result of criminal allegations.

In 2013 he twice attempted to take his own life.

His legal team are considering the possibility of appealing against the conviction.