The teens, who cannot be named for legal reasons, were aged 15 and 16 when they attacked Mr Akbar inside a Queanbeyan Caltex and left him for dead during a violent rampage in April 2017.

The older teen pleaded guilty to murder on Monday - just before his judge-alone trial was due to begin.

He also admitted robbery with an offensive weapon causing grievous bodily harm, assault occasioning actual bodily harm and stealing a car during the crime spree.

He had been due to face a jury trial last week, but that was scrapped after the younger teen entered pleas of guilty to murder and a carjacking-related charge.

Graphic security footage from the night of the murder was shown at a bail hearing for the younger defendant in February last year.

In the footage Mr Akbar could be seen entering the service station with the two teenagers.

As he walked towards the counter, one of the two in the footage - identified in court as the then 16-year-old - followed him and appeared to stab him.

Mr Akbar could then be seen running back towards the entrance while the offender chased him and continued to stab him.

The person identified as the then 15-year-old appeared to take what was believed to be a tyre iron from his clothing and removed the till from behind the counter.

The pair then smashed the front doors to leave the service station.

Mr Akbar grew-up in Karachi, Pakistan, and migrated to Melbourne on a skilled visa in 2009 to become a mechanic. Six years later he moved to Queanbeyan, sending money home to Pakistan and nursing dreams of one day bringing his family to Australia. Friends described him as responsible, charming and a generous son.

Both teens are due to face a sentencing hearing on October 31.

AAP and staff reporters