Unprovoked violence, paranoia behind prison killing

·3-min read

A prisoner who threw a single punch causing the death of his "best mate" - an accused murderer - says jail is a messed up game of survival.

Isaac James Martin told authorities the death of Zlatko Sikorsky may have been payback or karma for what "old mate" did to a young kid.

The now 29-year-old, who wore handcuffs and ankle shackles in Brisbane Supreme Court, also claimed he was paranoid about being attacked.

But the overt unprovoked violence that Martin was capable of may be impossible to understand, Justice Martin Burns said.

Martin was serving an eight-year jail term, but had more than a decade added to his time behind bars on Friday after admitting the unlawful striking causing Sikorsky's death.

Sikorsky was rushed from Brisbane's Wolston Correctional Centre to hospital with critical head injuries on November 10, 2020.

The 37-year-old died 10 days later.

He was accused of murdering and torturing 16-year-old Larissa Beilby on June 23, 2018, and had been awaiting trial.

Her battered body was found inside a barrel on the back of a ute abandoned at a residential complex on the Gold Coast.

Martin and Sikorsky occupied adjacent cells and appeared to be close friends, working together in the kitchen and doing fitness training together, prosecutor Philip McCarthy KC told the court.

Security video showed the two men talking with "no visible animus" for over a minute after cells were opened shortly before midday.

Martin punched Sikorsky to the left side of his face and neck before walking downstairs into the yard.

Sikorsky stood for about 10 seconds then fell face first onto the floor.

Martin cried telling prisoners: "I don't know what I've done. He was my best mate. Can you tell him I'm sorry?"

Later Martin said he did not remember much about the incident and had been paranoid about being beaten or poisoned.

But when told of Sikorsky's death Martin responded: "I don't give a f*** about old mate ... Maybe God let it happen for a reason. Maybe payback or karma for what he did to that young kid."

Sikorsky's death was the loss of a lifetime, his sister told the court.

"I've never felt more pain - it was so physical it hurt," she said tearfully.

Martin refused to accept crown documents in prison, telling authorities: "I know word for word what I have to say and don't need more paperwork."

Representing himself, Martin told Justice Burns jail is a "messed up game of survival".

He had asked to see supervisors before the incident and was "very paranoid" about being attacked.

Martin's criminal history includes bashing a man with a hammer after drinking coffee together at a friend's house in 2014 and assaulting prison officers five years later.

He was eligible for parole after serving sentences for those crimes in July, but Justice Burns added a further prison term of 11 years for causing Sikorsky's death.

He found Martin did not fully understand why he hit Sikorsky but the link to the murder accusations was unlikely.

Justice Burns took into account the prisoner's upbringing, with his father jailed for murder and arson.

His mother would beat the children if they didn't sleep then leave them on the side of the road, saying she hoped someone would take them.

"You are afflicted with a constellation of mental health problems," Justice Burns told Martin.

These combined to make him a person capable of acts of overt violence that are unprovoked and impossible to understand.