A MAN has been sentenced to life in jail for murdering his ex-partner's boyfriend after a dramatic twist in his trial in Bundaberg Supreme Court.
At the start of his trial on Monday, Jason Errol Gerhardt, 45, pleaded not guilty to murdering father-of-three Craig Marshall, 44, on August 1, 2015, at Coonarr.
Mr Marshall was the new boyfriend of Kristen Eastley, who split up with Mr Gerhardt in 2012.
But late on Thursday, he sensationally changed his plea to guilty.
Justice Roslyn Atkinson yesterday jailed Gerhardt for life for the murder, and also convicted him of bashing the former neighbour of his ex and the mother of his children, Kristen Eastley, in 2013.
An emotional Ms Eastley was in court for the sentencing after giving evidence earlier in the trial.
On July 31, 2015, Gerhardt organised for a friend to drive him from Hervey Bay to Ms Eastley's Coonarr house.
He took a knife from a shack near the house before making his way to the house, where he saw, through a glass door, Ms Eastley and Mr Marshall kissing.
Enraged, he rushed into the house and began attacking Mr Marshall.
Ms Eastley told the court she saw Gerhardt punch Mr Marshall on the back and heard a "pop" sound.
She managed to restrain Gerhardt, allowing Mr Marshall to flee into the backyard.
But Gerhardt broke free and chased down Mr Marshall and continued the attack, witnessed by one of Ms Eastley's sons.
Crown prosecutor Greg Cummings said Mr Marshall had suffered nine wounds but had died from two stab wounds that punctured both his lungs, causing haemorrhaging in one and instantly collapsing the other.
Mr Cummings said Mr Marshall's chest cavity had filled with 1.5L of blood and he was dead within minutes.
He said Mr Marshall's attempts to escape Gerhardt would have hastened his death.
Defence barrister Callan Cassidy said his client maintained he'd been in a relationship with Ms Eastley leading up to the murder.
Justice Atkinson yesterday read victim impact statements from Ms Eastley, three of her children and Susan Marshall, Mr Marshall's sister.
"Jason's actions not only took away the two most important people in my children's and my lives, his actions also, on a certain level, left me alone, and to be alone is to be a butterfly with a hole in its wing," Ms Eastley wrote in her statement.
"Jason took a life ... and a dad to three other children."
"He also took my children's daddy away from them.
"He also took a part of me, as a big part of me died with Craig that night."
Justice Atkinson also read victim impact statements from Ms Eastley and Mr Gerhardt's son and daughter.
"We have all changed a lot after what happened," the couple's son wrote.
"Marshy (Mr Marshall) was really nice and never raised his voice and always helped with our homework."
Mr Marshall's sister, Susan, said her brother was the youngest of nine children, the father of three of his own and "friend of many".
She said his death had devastated his children, her children and led her to seek counselling.
"There are days I didn't want to go but somehow found the strength," she wrote.
"No matter what sentence is handed out today, it will never be justice for Craig's life."
Justice Atkinson said she had no choice but to sentence Gerhardt, who sobbed throughout proceedings, to life in jail, and that one of the most telling aspects of the case was the fact he had picked up the knife on the way to the house.
"You took the life of a 44-year-old man for no other reason than that he was in an affectionate relationship with your ex-partner," she told Gerhardt.
"We must not forgot that the real victim of this has been Mr Marshall, whom you killed, who has no life.
"You took away that life in anger and in jealousy, and he certainly didn't deserve any of that."