A West Australian businessman has been found guilty of assaulting a teenager during an attempted citizen’s arrest.

After a four-day trial, a magistrate on Wednesday ruled that Esperance man Paul David Mack, 53, repeatedly punched Logan Ashton Brown, 18, during an incident in Castletown last year.

Magistrate Giuseppe Mignacca-Randazzo found Mack, a self-employed truck driver, had lawfully pursued and tackled the victim before “crossing a boundary” into unlawful action.

“The accused’s punching was unnecessary and not a reasonable response,” Magistrate Mignacca-Randazzo said.

In WA citizens have the power to arrest another person under the Criminal Investigation Act.

But a lawful citizen’s arrest must have sufficient cause and cannot involve the use of excessive force.

Victim ‘scared’, witness ‘in shock’

The court heard that at about 7:40pm on January 7, 2023, Mr Brown, then 17, had been walking to a party with a group of friends when they decided to take a shortcut across a vacant block.

In doing so, one of Mr Brown’s friends forcibly removed a fence panel belonging to Mack’s neighbour, Cameron Fairhead.

The two men then pursued the group of teens on foot, which resulted in Mack tackling Mr Brown near a local park.

Magistrate Mignacca-Randazzo said Mack’s actions until this point were justified and noted that police had been called and were on their way.

But he found that Mack “lost his sense of good judgement” in repeatedly punching Mr Brown while he was pinned to the ground.

On day one of the trial Mr Brown told the court he felt “scared” during the attack.

While giving evidence last week Mack denied punching the teenager and said he had “never hit anybody” in his life.

But the magistrate “positively believed” the account of bystander Dillan Ward, described as a “reliable witness”, who said Mack’s behaviour left him “in shock”.

While the exact number of punches was unclear, it was found that Mack “acted simultaneously with Mr Fairhead to inflict multiple punches”.

‘Loss of good judgement’

Mr Fairhead previously pleaded guilty to common assault.

Magistrate Mignacca-Randazzo said he did not believe evidence from police that Mack was intoxicated at the time and found that he acted out of frustration.

“They saw the damage done by people who were simply too lazy to walk around,” he said.

“The accused’s frustration and sudden loss of good judgement does not detract from that fact that punching Mr Brown was unlawful.

Mack was not present at Esperance Magistrates Court on Wednesday and listened to the verdict via audio-link.

He will be sentenced on Monday, April 15.

Speaking outside the court, Mr Brown’s mother, Jennel Brown, said she was relieved.

“It is acknowledgement that this did happen to Logan — that’s all we wanted,” she said.