Former CFMEU official Paul Tzimas told the royal commission that Mick Gatto attended a meeting convened after an attack at a construction site in which a union official and his colleague were injured. Tzimas was the first witness linked to the Construction, Forestry and Maritime Employees Union (CFMEU) to appear before the royal commission into the integrity of major public and civil infrastructure construction projects in Victoria.

Tzimas told the commission on Wednesday that he sustained a fractured ankle. His colleague was left with a shattered eye socket, dental damage, severe post-traumatic stress disorder (PTSD) and partial loss of vision following the attack by individuals linked to builders and investors. He confirmed that he believed the attackers may have been connected to the outlaw bikie gang. Tzimas is a former CFMEU official who left the union in January and is now unemployed.

Approximately a week after the attack, a meeting was held between union officials and builders, who also arranged for Gatto to attend. Tzimas explained that Gatto is known for working for investors and builders to resolve issues with their projects. He added that Gatto later gave him a gold bracelet, which he initially refused.

He agreed with assistant counsel Chris Carr that he first refused the gift because he knew it could be "considered inappropriate for someone in your position to accept a gift from someone on the other side of the fence". After speaking with Gatto about the reason for the gift, he decided to accept the bracelet. Gatto told Tzimas that it was not his way of earning any service, that he had a bad opinion of him as an official, that he believed he may have judged him too harshly, and that it was an olive branch for people he considered friends. "I have never worn it or anything," Tzimas said, adding that he knew other union officials had also received gold bracelets from Gatto.

Tzimas was also questioned about a letter written by the CFMEU on behalf of a man convicted of negligent homicide who was seeking parole, which confirmed that he would be offered a job. He said he was not clear why the union had helped that man, but added that "his father was a union delegate at the time... so that probably also carries some weight". Carr also read out the names of 15 men to Tzimas and asked if they were all union members and connected to bikie gangs; Tzimas agreed that 11 of them were.

The project to remove the rail-road crossing on Gap Road in Sunbury, north of Melbourne, is in the focus of the commission's hearing. Tzimas attended the worksite as part of a union action that ultimately halted construction. He was also present at a meeting between project managers and union officials at the CFMEU headquarters on 7 June 2022, which led to the resumption of work. The commission previously heard that at that meeting, the union demanded that its own health and safety representative and a union-affiliated traffic management and labour hire company be installed on the Gap Road project for work to continue. The hearing before Commissioner Christopher Kourakis continues.