A father who dived over a table and stabbed his estranged partner to death during a courthouse mediation session has been jailed for at least 24 years.
Paul Gary Turner, 43, smuggled a knife into a meeting with Sarah Marie Thomas, 33, at Joondalup courthouse in Perth on December 20, 2016.
Turner, who was trained in ‘commando’ techniques, stabbed her six times in front of a horrified court officer, severing her carotid artery.
A Western Australian Supreme Court justice on Tuesday sentenced him to life in jail with a non-parole period of 24 years.
Sarah Marie Thomas, 33, was murdered in December 2016 when her estranged partner stabbed her six times including three in the neck
The couple were together for eight years before they broke up in August 2016 and argued over money and custody of their two children.
Ms Thomas’ murder was filmed on CCTV and played in court where Turner admitted it ‘appeared’ he killed her but claimed to have no memory of it.
A jury took just two hours to find him guilty in August, which drew gasps and sobs from his supporters in the public gallery.
Turner’s entire defence was that his actions were not conscious because he was having a dissociative seizure brought on by a 2015 workplace injury at the time.
However, his own medical expert witnesses testified there had never been a case of someone in a dissociative state committing a violent act.
Paul Gary Turner (middle), 43, smuggled a kitchen knife into a pre-trial conference at Joondalup courthouse in Perth and stabbed her to death

Turner was captured on CCTV footage sitting in the waiting room outside the meeting before the attack with a lever arch folder. The knife was either hidden there or in his shorts pocket
Prosecutor James Mactaggart dismissed Turner’s claim as ‘nonsense’ and told the court he planned to kill Ms Thomas in an ‘outrageous act of evil’.
‘This was someone perfectly normal contemplating the evil deed he was going to commit, planning and plotting in his mind. He knew what he was doing. He was functioning quite well,’ he said.
‘He turned up with a knife. He had, in the state’s case, formed an intent to take her life.’
Turner was captured on CCTV footage sitting in the waiting room outside the meeting before the attack, peering into a lever arch folder.
Mr Mactaggart said he either hid the knife in there or in his pocket.
About four minutes into the meeting, the registrar ran out of the room before Turner emerged and slid against a wall to the floor, where he sat until detectives and security guards rushed over to arrest him.

One of the stabs cut Ms Thomas’s (pictured) carotid artery, which killed her within seconds
At his Supreme Court of Western Australia trial, he wept as he claimed the last thing he recalled on the morning of the killing was speaking with their children.
Turner said his next memory was being in a police station with blood on his hands.
He insisted that after he had an accident while working as a truck driver in 2015, he suffered symptoms including seizures that caused blackouts, sometimes lasting more than 45 minutes.

The pair were embroiled in a custody dispute in the days leading up to the attack and were meeting with a registrar at the Joondalup complex over Turner’s separate claim Ms Thomas (pictured) owed him money
Turner said he had no recall, but after he was played CCTV footage of the waiting room outside the meeting – which showed him slide to the floor after the registrar ran out – he admitted he killed her.
‘It appears that way,’ he said. ‘I didn’t intentionally kill her.’
Mr Mactaggart dismissed Turner’s claims as ‘a pack of absolute lies’, saying he was fully aware of what he was doing, and had spent more than 100 hours getting neurological tests but his results kept coming back normal.
He was humiliated Ms Thomas had got the better of him in a bitter custody dispute, obtaining a court order to recover the children days earlier, and she refused to settle with him at the meeting over his claim she owed him money, the prosecutor said.
Defence counsel Lisa Boston argued her client had experienced insane automatism, telling the jury in her closing address that it would have been ‘bonkers’ for a man trained in commando knife techniques to knowingly kill someone in a complex packed with security guards and police.
Turner trained in lethal artery-slashing and knife concealment when he was aged in his late 20s, and continued to practice during his eight-year relationship with Ms Thomas.
Asked about this interest, Turner replied it was ‘for the historic aspect’ as he studied the Fairbairn system used in WWII.

Turner earlier admitted that in the mid-2000s, he had trained in lethal commando weapons techniques up to three days a week for about three years, learning how to swiftly kill by cutting various arteries, including the carotid (pictured is the knife allegedly used by Turner)