Plaque unveiled for man who died trying to save teenager

A security guard who was allegedly stabbed to death at a train station in Melbourne's outer north has been honoured with a permanent tribute.

Aidan Becker, 22, was killed when he allegedly tried to rescue a 14-year-old boy from an alleged machete attack at Mernda train station on March 6.

Four teenage boys have been charged with his murder, while a 16-year-old girl was charged with robbery, theft, hindering and assaulting police.

Today, Mr Becker's family was surrounded by a small group of supporters at Mernda station, where they unveiled a plaque commemorating his bravery and kindness.

The plaque was fixed to a pillar in the station's busy thoroughfare, where Mr Becker died from his fatal knife wounds, and read: "Not all heroes wear capes, some walk among us changing lives forever.

"Gone but never forgotten."

Members of the CFA and SES also attended to show their support.

A small group of police officers patrolled the area this afternoon.

Allegedly attacked after shift as security guard

Mr Becker was on his way home from work as a security guard at The Alfred hospital when he allegedly intervened in the brawl.

He led the schoolboy away from the attack, but the group then allegedly turned on him, stabbing him to death before fleeing.

In a social media post ahead of the unveiling, Mr Becker's mother, Natalie Becker, wrote: "We would like to once again thank all members of the community for the love, kindness, and sympathy you have shown our family during this difficult time."

In March, thousands of mourners gathered at the train station for a candlelight vigil for Mr Becker in the wake of his death, with a sea of floral tributes and messages for the young man filling the area where his alleged murder unfolded.

Among them was a card written by the teenage boy whom he allegedly assisted.

'Hold no guilt'

In an interview with YouTube channel, Australia First Media, in late March, Ms Becker told the surviving boy to live his life to the fullest.

"Hold no guilt because my son is back with God and would want you to live with love, and do that in his honour," she said.

Mr Becker, a keen North Melbourne supporter whose friends described him as their bodyguard, has been remembered as a kind young man who wanted the best for everyone.

His sister Siobhan said: "He would do all of it again, even knowing the awful outcome. I don't think he would hesitate in any way to do it again."

The teenagers will return to court at a later date.