A teenager has pleaded guilty to the murder of a young man who was brutally stabbed to death while working at a petrol station near Canberra.

Zeeshan Akbar, 29, was killed while working at the Caltex service station on Bungendore Rd in the NSW town of Queanbeyan in April 2017.

His body was found by a colleague shortly before midnight.

The 19-year-old offender, who was 16 at the time and on a violent rampage with a 15-year-old boy, was due to face a judge-alone trial today before Justice Geoffrey Bellew at the NSW Supreme Court in Sydney.

But three hours after it was due to start, he pleaded guilty to the murder of Pakistani-born Mr Akbar.

In a high-pitched voice, he also entered guilty pleas to being armed with an offensive weapon — a knife — and wounding Mr Akbar as he robbed him of money and cigarettes.

He admitted to wounding another man, Sankalpa Mahatara, the next day with intent to cause grievous bodily harm, and taking and driving Mr Mahatara’s silver Ford Falcon sedan without consent while intentionally inflicting actual bodily harm.

The Crown accepted the four guilty pleas.

Members of Mr Akbar’s family from Pakistan were in court today. One woman cried and clutched tissues to her face as the confessions were made and was then comforted by relatives.

They were too distressed to speak to reporters after proceedings but are now expected to file victim impact statements.

The older teenage killer, who cannot be identified as he was a juvenile at the time, sat expressionless in the dock during proceedings with a green prison jumper draped over his shoulders.

His co-accused, now 17, last week pleaded guilty to murder and the aggravated taking of a motor vehicle while a person — Mr Mahatara — was inside.

As he was led away on Wednesday, a woman in the public gallery sobbed and called out to him.

Justice Bellew intends to sentence the teenagers together.

He listed them for a sentence hearing on October 31 with adequate security arrangements.

The facts of the offending have not been resolved between the prosecution and defence in either of the boys’ cases after their 11th-hour pleas. They are due to be filed to the court by October 17.

NSW Police in April 2017 said they were investigating the killing of Mr Akbar as a possible act of terrorism due to “physical evidence” discovered at the scene.

Reports at the time said a word, which appeared to be an attempt at the word “IS”, was allegedly scrawled in blood on the service station window however then-NSW Deputy Police Commissioner Catherine Burn refused to comment on the nature of the evidence.