Last Friday morning's incident, where a 31-year-old male was taken to Lismore hospital with serious head injuries, and the body of a 25-year-old man was discovered near Clifford Park, is still under critical police investigation under Strike Force Pineshaw.

Northern Region Commander, Assistant Commissioner (AC) David Waddell APM, yesterday was asking for any witnesses to come forward.

"It appears there was an affray, some type of a brawl in the vicinity of Clifford Park, and those matters are still under investigation. Police are appealing for witnesses to come forward, anyone that may have any dash cam, CCTV footage or may have any information in relation to that homicide and report it to Crimestoppers or the Lismore Police Station.

"As a result of information over the weekend, on Sunday, I declared a critical incident investigation just to look at the police response, and to look into that investigation and initial incident."

AC Waddell said they believe up to 20 people were involved in the brawl and that they were known to each other. "But the motives in relation to the investigation are still ongoing."

"Look, we've interviewed plenty of witnesses and residents. We've done a lot of canvassing. We've obviously processed all the crime scene, so a fairly substantive investigation by regional detectives and the homicide squad, as well as other specialist units. And that investigation will be ongoing.

As for the man airlifted to Gold Coast Hospital, he is still in a serious but stable condition. Police will be questioning him. "Once he's in a medical condition to speak with us, we will be speaking to him, trying to establish more facts as to what occurred."

AC Waddell wouldn't be drawn into the cause of death, saying it was the subject of a post-mortem.

Police have been concerned about retribution and keeping the peace around the Goonellabah area.

"Firstly, we are very engaged with the families of the deceased parties, so we've made contact with them. We are engaged with the community. We have Aboriginal Community Liaisons deployed as well as additional police resources, just to make sure there's not any community unrest or concerns around public order.

"We are worried about potential retribution. We won't ask people who are involved to just let us do our job. We will take action and arrest those that are responsible.

If anyone has any concerns for their safety, report it to police, and they will take action.

AC Wadell confirmed that the investigation includes the original response of police, "And the appropriateness and timeliness of that response. There have been no charges at this stage. The investigation is still in its early phase stages."

At this early stage of the investigation, police are still trying to identify the people involved in the brawl, but they do expect to take action where they identify offences.