Details of Teparat Tepsut's jail sentence had been suppressed during the trial of two other men accused of murdering Mr Mitchell but were revealed to the jury on Thursday.

Tepsut,  the son of a Thai army Major-General who claimed he did not take part in the attack on Mr Mitchell but stood guard for the other two men, told the court he had been jailed for 15 years with a non-parole period of 11 years after pleading guilty to murder.

Tepsut agreed that if he had not pleaded guilty and agreed to co-operate by being a prosecution witness, Justice Christopher Beale would have jailed him for 24 years with a minimum of 18 years.

Two other Thai nationals, Thatiya Terdputham, 40, and Sarud Seehaverachart, 32, are standing trial after pleading not guilty to murdering Mr Mitchell on May 24, 2009.

Mr Mitchell, 29, had been enjoying a night out with his sister-in-law Daniella and her friends at Brunswick when they saw the Thai men attacking a bystander who had asked them to stop arguing with a woman outside a massage parlour.

Daniella called out to the men to leave the man alone and they confronted her before Luke stepped forward to protect her.

Mr Mitchell was punched and kicked but managed to fight back and get the better of the Thai men before being dragged away by Daniella.

Mr Mitchell, his sister-in-law and friends then drove to the nearby 7-Eleven on Sydney Road to buy cigarettes.

Crown prosecutor Andrew Tinney, SC, has told the jury that all three Thai men were armed with knives and a meat cleaver when they went searching for Mr Mitchell to teach him a lesson before spotting him at the 7-Eleven.

Mr Tinney said the three men had been part of a joint criminal enterprise to kill or seriously injure Mr Mitchell in what was a violent, terrifying attack.

An autopsy revealed Mr Mitchell had been stabbed three times in the chest, once in the stomach and twice in the right arm.

Tepsut admitted he was armed with a knife in each hand at the time but claimed he did not take part in the attack on Mr Mitchell, just stood guard for his friends.

All three men flew out of Australia on one-way tickets to Bangkok hours after the attack.

The trial continues.