A man who was trained in "commando knife skills" smuggled a weapon into a Perth courthouse complex and deliberately fatally stabbed his former partner during a meeting about money, the WA Supreme Court has been told.
Paul Gary Turner, 43, is on trial accused of murdering the mother of two of his children, 33-year-old Sarah Marie Thomas.
She died almost instantly after suffering six stab wounds including three to her neck, one of which hit her carotid artery, at the Joondalup Justice Complex in December 2016.
The court has been told the couple's eight-year relationship had broken down and they were meeting, in the presence of a registrar, at the courthouse to try to resolve a dispute over money Mr Turner claimed he was owed by Ms Thomas.
Prosecutor James Mactaggart said after Ms Thomas told Mr Turner she would not offer him any money, he stabbed her before dropping the knife and going out into the waiting room, where he sat down.
Mr Mactaggart said it was the state's case that Mr Turner had used the skills and knowledge he gained through "commando" knife training to murder his former partner.
He said about a decade earlier Mr Turner had trained in martial arts and had learnt different techniques about using knives to inflict fatal injuries in humans, including how to pierce arteries and vital organs.
Neck wound not survivable, court told
Mr Mactaggart said Mr Turner had hidden the knife either in the pocket of his shorts or in a folder he was carrying before attending the meeting, where he knew that Ms Thomas would be representing herself.
He said the stabbing happened when the registrar turned his head for a brief moment.
"[The accused] took the opportunity to retrieve the knife and he literally stabbed Ms Thomas to her certain death."
Mr Mactaggart said the wound to Ms Thomas's carotid artery was not survivable and he claimed that Mr Turner had "by reason of his training" inflicted that wound to deliberately and intentionally cause her death.
"He knew quite well how to deploy a knife to inflict fatal injuries," he said.
"He knew that would cause the greatest amount of damage."
Knife skills learnt from British paratrooper
Mr Turner has pleaded not guilty with his lawyer, Lisa Boston, admitting her client had trained in commando knife techniques, in particular those of WE Fairbairn — a British paratrooper who developed hand-to-hand combat methods.
The court was shown a document called "the Fairbairn-Sykes fighting guide" which outlined stabbing techniques and what was called "a timetable of death".
A statement was also read from a man who was now dead but who had trained Mr Turner, including in "weapons awareness techniques".
The trial is set down for nine days.
