The investigation into the fatal stabbing of a teenager at Sydney’s Royal Easter Show is being frustrated by a lack of co-operation from potential witnesses.

Police have still not identified the person who stabbed 17-year-old Uati “Pele” Faletolu on April 11, despite hours spent reviewing CCTV footage of the incident.

Many people witnessed the brawl and stabbing and might have video but were yet to come forward, Homicide Squad Commander Danny Doherty said.

“It’s not the time now to stay silent,” he said on Tuesday.

Pele Faletolu with girlfriend Taylor Piliae. Photo: Instagram

Mr Faletolu was working as a ride attendant at the busy show when he was caught up in a brawl between two young groups. A second boy was stabbed in the leg at the same time.

A 15-year-old has been arrested and charged with carrying a knife. He has not been charged over Mr Faletolu’s death.

Detective Superintendent Doherty said plenty of people might have unknowingly captured footage of the stabbing, which in the main carnival area on a day when 80,000 people are estimated to have visited the show.

“They may think it’s inconsequential but it could be incredibly important to us,” he said.

“They may have captured unknowingly or inadvertently who is actually responsible for [the] stabbing.”

Detective Superintendent Doherty said people might not come forward because they thought they had no any useful information, or they felt they had to stay “staunch”.

One teenager who had been arrested had not helped the investigation, which Detective Superintendent Doherty attributed to “misguided loyalty”.

He said the family of the victim was being as supportive as possible.

“It’s the associates of the group that really frustrate us,” Detective Superintendent Doherty said.

“There’s a 15-year-old who obviously would know and there’s a 16-year-old who would know as well. There’s other people who would know.

“So far, they’ve lost their mate and close associate and they’re not coming forward.”

Misguided loyalties and a code of silence were preventing people coming forward, but now was the time for action, Detective Superintendent Doherty said.

Theories that the brawl might have been pre-arranged between rival groups are a strong line of inquiry.

“But until we know who’s involved, we’ll never know what the motive may be,” he said.

-with AAP