Their court appearances on Thursday came as police and other emergency services workers combed through areas of Canberra's inner north, including Haig Park, as part of their ongoing homicide investigation.

Frederick Elijah Mercy Tuifua was formally charged in the ACT Magistrates Court on Thursday morning with the murder of Canberra Comanchero commander Pitasoni Tali Ulavalu.

The 26-year-old, from Silverwater in western Sydney, did not enter a plea or apply for bail, which was refused.

Police allege that Mr Tuifua stabbed Mr Ulavalu in the neck during a fight at Kokomo's in Civic last month.

It is believed that Mr Ulavalu, 48, was stabbed inside the venue before he died on the footpath outside in the early hours of July 19.

Two other men - Matthew Kupu, 22, and Osaiasi Avanua Sydney Kupu, 23 - also appeared in court on Thursday morning, charged with affray in relation to the Kokomo's incident.

Charges read to the brothers by Chief Magistrate Lorraine Walker allege that they "engaged in violent conduct" towards Comanchero bikie Zachary Robb and another man, named as Shane Haughton.

Like Mr Tuifua, the Kupus live in western Sydney and did not enter pleas or apply for bail.

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Police arrested the trio in Garran in the early hours of Wednesday after they and a fourth man turned up at a hospital emergency department.

The fourth man, Maximilian Ellis Kurt Budack, had been shot three times and required emergency surgery.

Police are investigating the circumstances surrounding the shooting, and it remains unclear exactly where and when it occurred.

Mr Budack, who is understood to be a Canberran, remains under armed guard in hospital and has also now been charged with affray in relation to the Kokomo's incident.

He too was remanded in custody following a bedside court hearing on Thursday afternoon.

All four of the accused are due to appear in court again on August 25.

Meanwhile, authorities were on Thursday conducting an extensive line search of areas in the inner north Canberra suburbs of Braddon and Turner as part of Operation Hanok, the cross-border investigation into Mr Ulavalu's death.

The large-scale search, which is expected to continue for several days, involves uniformed police, detectives, police search and rescue, firefighters and members of the State Emergency Service.

Police would only say they were looking for "additional evidence", but the most probable item sought now is the gun used in the shooting of Mr Budack.

A day earlier, Detective Superintendent Scott Moller told media that police had been "looking at a group of men for some time" in relation to Mr Ulavalu's death before an opportunity to make arrests "presented itself" at the hospital.

He said those charged were not bikie gang members, but police had established links between the men and the Comancheros.

Detective Superintendent Moller said investigators were speaking to more than 200 witnesses as part of the homicide probe, as well as reviewing hours of CCTV footage.

Documents tendered to the ACT Magistrates Court in related proceedings reveal "numerous" Comanchero bikies were involved in the fight at Kokomo's.

"The really troubling factor of this is that it involves members of outlaw motorcycle gangs," Detective Superintendent Moller said.

"They're not willing to discuss things with police, usually, so this is a particularly complex matter.

"I certainly expect there'll be further arrests and more charges laid."