A Hells Angels bikie has been jailed for at least 23 years for the “tragic, brutal and totally unnecessary” bashing murder of “innocent bystander” Mark Boyce, whose death has inflicted “unimaginable grief” upon his family.

Tobias Sahlstorfer, 35, was found guilty of the January 2017 crime earlier this year after a Supreme Court trial before Justice Laura Stein, in the absence of a jury.

In sentencing on Thursday, Justice Stein said Sahlstorfer, of Gulfview Heights, was the first of three men to attack Mr Boyce, using his “fists and feet as weapons”.

She said the three men inflicted a “flurry of punches and kicks which continued after Mr Boyce was on the ground”.

Tobias Sahlstorfer was a member of the Hells Angels at the time of the attack.(Supplied: Facebook)

“The beating was short and brutal and rapidly rendered Mr Boyce unconscious,” Justice Stein said.

“Mr Boyce did not fight back.”

She said Mr Boyce, 36, was not the intended target of the attack and that Sahlstorfer and two other men were instead looking for Mr Boyce’s friend when they drove to Hill Street, Elizabeth South, on the night of the bashing.

“Mr Boyce was an innocent bystander who became a victim of your attack when you could not locate [the intended target],” Justice Stein said.

She said Mr Boyce had “fled down the street” after an initial interaction with Sahlstorfer, but one of the other men present chased down and captured Mr Boyce.

They rendered him “incapable of defending himself”.

Justice Stein said Sahlstorfer, who briefly shook his head as the sentence was handed down, had not shown any remorse for his actions.

“The tragic, brutal and totally unnecessary killing of Mr Boyce has inflicted unimaginable grief, loss and anguish upon his parents who have lost their only child.”

Tobias Sahlstorfer will be eligible to apply for release on parole in August 2043.(ABC News: Che Chorley)

“Their profound suffering is still palpably raw seven years later … it will continue for the rest of their lives.”

She said Sahlstorfer, who was born in Germany, was a member of the Hells Angels at the time of the attack.

“Your association with the Hells Angels is relevant to your prospects of rehabilitation and consideration of general and personal deterrence,” she said.

Justice Stein said she accepted Sahlstorfer had not intended to kill Mr Boyce, but it was “brutal and blows were delivered with sufficient force to cause a fracture and brain injuries which ultimately resulted in Mr Boyce’s death”.

‘He was the only child I had’

Mr Boyce died after a week in hospital on February 8, 2017.

In 2019, another man, Joshua Roy Grant, was found guilty of murdering Mr Boyce after an earlier trial and was sentenced to 20 years’ jail.

A third man believed to be involved has yet to be arrested.

Mark Boyce died in hospital just over a week after the assault.(Supplied: SA Police)

Police have previously said a vehicle involved in the attack was found cut up, burned and buried more than 4 metres underground on a Hells Angels Club property at Ponde in the Murraylands.

As he left the court after Sahlstorfer was sentenced Mr Boyce’s father, Malcolm Boyce, gripped a framed photo of his son.

He has previously said his son “was no angel, but he was my son” and had been “in the wrong place at the wrong time”.

“I miss my son every day, he was the only child I had,” he said after an earlier hearing.

Michael Woods, for Mr Sahlstorfer, said he had spoken to his client after the sentence was handed down and that he was doing “as well as expected”.

Sahlstorfer, who has been in custody since his arrest in August 2020, must serve a mandatory life sentence for Mr Boyce’s murder.

He will be eligible to apply for release on parole in August 2043.