Dozens of police assembled on the banks of the Leschenault Inlet near the Bunbury CBD on Thursday evening after he allegedly strapped explosives to his body and sat in front of a hostage.

The siege came to an end early on Friday morning. After the hostage was released police fired two non-lethal rounds before swarming and arresting Mr Batty.

Mr Batty also triggered a similar siege situation in Kings Park in 2012 following which he was charged with several offences including aggravated assault with intent to commit a crime, attempting to cause an explosion with intent to destroy or damage property, and deprivation of liberty.

Police closed down part of Kings Park in July 2012 after they became aware of Mr Batty, who was in an agitated state, parked in his car and held a barbecue gas bottle and a cigarette lighter.

It was alleged by police that Mr Batty had also held his then 79-year-old father Frank as a hostage in the car, with his wrists bound with tape. However, Frank was able to escape from the car before police arrived.

Police attempted to negotiate with Mr Batty before Tactical Response Group vehicles fired non-lethal bean bag rounds at the vehicle and then rammed it when he attempted to drive off. 

Mr Batty was then taken into custody by police and a hospital order was made to assess his mental health before court proceedings.

The report, from Graylands Hospital's maximum-security Frankland Centre, said Mr Batty still required psychiatric care and was not fit to stand trial.

An arrest warrant was then issued for Mr Batty after he failed to appear in Perth's District Court for sentencing in June 2014.

Mr Batty, 52, had absconded from the Graylands Hospital and was last seen at the Claremont Quarter Shopping Centre on Thursday, June 19, 2014.

His escape sparked political discussion over the security of mental health patients in Western Australia which will be reignited following the Bunbury siege.

Opposition spokesman for mental health Stephen Dawson expressed concern at the time of Mr Batty's escape that a mental health patient was able to get away from a locked facility.

"It's an outrage that he's escaped and an outrage the minister hasn't informed the community that they could be a risk from this violent offender escaping," Mr Dawson told AAP in July 2014.

"The Frankland Centre previously submitted a report on Mr Batty that he still needed psychiatry care and was not fit to stand trial.

"If he still needed care and he's not fit to stand trial, he should still be detained."

Mr Dawson said Mr Batty's escape put the spotlight on Graylands Hospital, which also faced several inquests into a spate of deaths at the facility in 2013. He said the government's closure of wards at the facility could have compromised its security.

"If they've closed wards they probably have started to cut back on staff and this could have led to somebody who's got a violent past escaping from the facility."

► If you have mental health issues or need advice, call Lifeline on  13 11 44