Nelson, now 34, who had addresses at Windale and Merewether, was represented by solicitor Cameron Duncan when he appeared in Newcastle Local Court on Wednesday and pleaded guilty to armed robbery.

Nelson remains behind bars and will next appear in Newcastle District Court next month to get a sentence date.

The victim, a 25-year-old man, was working alone and had opened the store on the ground floor of the shopping centre about 7am on July 9 last year.

It was about 7.40am when Nelson was dropped off outside and made his way through the car park before heading towards Donut King.

At 7.47am he approached the counter while the victim was stocking the shelves with doughnuts.

He put his hands in his pockets and pretended he was looking for his wallet, but then produced a syringe.

Nelson removed the cap and put it on the counter and uttered a terrifying threat.

"This has AIDS in it," Nelson said. "I don't want to stab you. Give me the money. I don't want to do this."

The victim replied: "Are you sure you want to do this? There are cameras everywhere" and Nelson told him: "I'll jump the counter if I have to, I need the money".

The victim was "fearful that the red liquid in the syringe was HIV infected blood", according to an agreed statement of facts.

He handed over about $200 and Nelson ran away from the store and out of the shopping centre.

The victim rang shopping centre security and a short time later police arrived, interviewed the victim and obtained CCTV footage.

The next day, police found out that Nelson's mother was living in South Street, Windale, and went to the house where they found Nelson in the backyard.

He was arrested, and police found a number of syringes inside a small black satchel.

Police searched Nelson's room at the house and found clothing matching what he was wearing during the armed robbery.

Nelson was on bail at the time of the armed robbery, but prosecutors applied in July to have his bail revoked and he has remained behind bars since.