Bondi Beach terror suspect Naveed Akram's eyes lit up whenever he spoke about guns - and even bragged he was a better marksman than an Olympic sharpshooter.

Akram, 24, along with his father Sajid, 50, allegedly opened fire on a Jewish festival celebrating the first night of Hanukkah on December 14.

They are accused of killing 15 during the alleged terror attack, with dozens more rushed to hospital suffering life-threatening gunshot wounds.

Police allege the pair were carrying four firearms and four homemade bombs, and that Sajid, who was killed by officers during the attack, held a gun licence.

Daily Mail last week revealed Sydney tradie Rishy worked alongside the alleged mass killer for a year at the building site of the Crows Nest Metro station on Sydney's lower north shore.

Now Daily Mail can reveal Akram openly boasted about his firearm skills for years and even challenged a former Olympian, claiming his abilities were superior.

Akram would usually sit silently, arms crossed, saying little while his coworkers chatted about families and weekend plans.

But Rishy says everything changed when the subject turned to guns.

Naveed Akram's eyes lit up whenever he spoke about guns, says his former workmate

Naveed Akram (pictured) was a withdrawn worker having no real friends or social life

The suspected Bondi Beach terror attacker is alleged to have conducted firearms training at a location thought to be in the NSW Southern Highlands, pictured here in a court-released still from a video police allegedly found on his phone

'Nav had a really bad stutter, but no one would make him feel uncomfortable about it or laugh at him,' Rishy told the Daily Mail.

'He didn't even scroll on his phone or anything - just sat there watching everyone eat and unless someone spoke to him, he never said a word.

'Every morning I'd ask how his night or weekend was and it was always the same reply. 'Good good good, w-w-w-went to the gym,' same conversation every day, always stuttering.'

But he would suddenly come alive if the conversation ever turned to firearms.

'I already knew he had a gun licence,' he said. 'He told everyone and he was really really proud of that.

'It was the only time you really saw any kind of emotion from him and his eyes lit up when he talked about guns and he was animated when he spoke about them.'

Rishy says he had no real interest in firearms and their conversations never went into detail about how often Akram practised shooting, the types of weapons he owned or where he went to train.

But he vividly remembers the day a former Australian Olympian joined their crew as a subcontractor.