Zlatko Sikorsky death: Isaac James Martin, 29, pleads guilty over one-punch killing of Zlatko Sikorsky

A man who murdered his teen girlfriend and shoved her body in a barrel was killed in a brutal one-punch attack by a prisoner enforcer in an act of “payback or karma”.

An inmate who killed a high-profile murderer in prison told a guard that “maybe God let it happen for a reason” and it “may be payback or karma for what he did to that young kid”.

Zlatko Sikorsky, 37, was charged with murdering his 16-year-old girlfriend Larissa Beilby in 2018. He dumped her body in a barrel in the back of a ute in Stapylton on the Gold Coast.

He was committed to stand trial in late 2019 on charges of murder, interfering with a corpse, deprivation of liberty and torture.

However, Sikorsky fell victim to a one-punch attack in Wolston Correctional Centre on November 10, 2020, and died in the Princess Alexandra Hospital 10 days later.

Isaac James Martin, 29, pleaded guilty to one count of unlawful striking causing death in Brisbane Supreme Court on Friday.

The court heard Martin had a severe personality disorder, as well as narcissistic and psychopathic traits. These were largely blamed on his appalling childhood – his father served long stints in prison and his mother neglected and was violent towards her eight children.

Crown prosecutor Philip McCarthy said Siksorky and Martin were in adjoining cells and by all accounts were friends.

Zlatko Sikorsky (right) is seen in a police vehicle arriving to Maroochydore Police Station IN 2018 after a siege at an Alexandra Headland unit complex. Picture: AAP Image/Darren England

On November 10, 2020, all cell doors opened to allow prisoners to roam free. CCTV footage showed Martin and Sikorsky talking near the front of Martin’s cell for more than a minute.

“What can be observed is that there were no raised hands and no visible malice between the two,” Mr McCarthy said.

Suddenly, Martin punched Sikorsky on the left side of his face and neck. Sikorsky remained standing. Another prisoner asked him if he was alright, and Sikorsky responded: “Yes.”

But that prisoner observed that Sikorsky was not alright, and seconds later Sikorsky collapsed to the floor, hitting his head as he fell.

Outside in the yard, other inmates asked Martin what had happened. He said he “did not know” but was “going to hand himself in”. Martin also said Sikorsky was his “best friend” and that “he didn’t mean to hurt him”. Martin also said he was hearing things.

Sikorsky was rushed to the PA Hospital. He suffered a traumatic brain injury. His condition rapidly declined until he was taken off the ventilator 10 days later and died.

When Martin was told of Sikorsky’s death by a prison guard, he responded: “I don’t give a f***, I don’t really care.”

Larissa Beilby, 16, was murdered and her body was dumped in a barrel. Source – Instagram

When the prison guard asked whether the news was difficult to hear, Martin laughed: “Maybe God let it happen for a reason? Maybe payback or karma for what he did to that young kid?”

Martin has given varying explanations as to why he punched Sikorsky. But the common themes are that he believed Sikorsky, either alone or with others, was going to attack or poison him. He has since acknowledged he misinterpreted the situation.

Martin’s criminal history stretched back for a decade. The most serious offences were attempted armed robbery in 2013, before he was jailed for eight years for malicious acts with intent in 2016. He then received a further eight months behind bars for assaulting a prison guard.

He was serving those two cumulative sentences when he killed Sikorsky.

Martin legally represented himself on Friday. He told Judge Martin Burns that his attempts to tell prison guards that he was being targeted by other inmates had fallen on deaf ears.

“I would just like to say that jail is a messed up game of survival,” he told the court.

“I was very paranoid, I had recently had surgery because I had cut an artery, I wasn’t really sleeping very well.”

Sikorsky’s younger sister, who cannot be named for legal reasons, read a statement to the court during Martin’s sentencing.

Zlatko Sikorsky fell victim to a one-punch attack in Wolston Correctional Centre on November 10, 2020, and died in the Princess Alexandra Hospital 10 days later.

“Losing you was the loss of a lifetime … I just want my family back,” she said.

“I was lucky enough to know the real you. I know that you had a hard, tattooed exterior. But underneath it all, you were the one person who encouraged me. You were my cheerleader.”

Judge Martin Burns sentenced Martin to 11 years’ prison. He also ordered he must serve 80 per cent before being eligible for parole.

“You are afflicted with a constellation of mental health problems that combine in such a way as to make you not only an extremely challenging proposition for future treatment, but a person who is capable of acts of overt violence which are unprovoked and impossible to understand,” he told Martin.

Judge Burns said that apart from initially apologising to other inmates for hitting Sikorsky that day, Martin had shown no remorse for his actions.

“This was a completely unprovoked act which had a devastating outcome,” he said.

Martin’s previous sentences were due to be complete in July this year, his new 11-year sentence will start then.