A major development has emerged in the prosecution over the fatal street attack that claimed the life of 22-year-old James Callahan, with one of the accused admitting responsibility for his murder while five others continue to deny involvement and will stand trial.

Alivia Muriel Briggs, 35, appeared before Newcastle Local Court via video link from custody, where she pleaded guilty to one count of murder.

Her case will now proceed to the Supreme Court of New South Wales, where a sentencing timetable is expected to be confirmed in September.

The guilty plea marks the first admission of criminal responsibility among the group of people charged over the death of Mr Callahan, who was fatally stabbed and assaulted in Hamilton, Newcastle, during the early hours of 17 November 2024.

Police allege the violence began after Mr Callahan made a brief comment asking members of a nearby group not to litter while he and a friend were eating outside a late-night kebab shop.

According to police allegations tendered before the court, the initial confrontation quickly escalated.

Investigators allege Briggs left a vehicle after the comment was made, while another member of the group assaulted Mr Callahan.

Although Mr Callahan and his friend attempted to leave the area, police allege the group regrouped, followed them in multiple vehicles and later carried out a coordinated attack further along Beaumont Street.

Police have alleged that during the second confrontation several members of the group shouted phrases including “smash him” and “kill him” while Mr Callahan was repeatedly assaulted.

Investigators allege Briggs stabbed Mr Callahan in the chest while others punched, kicked and struck him with a metal pole.

Police further allege Briggs’ brother, Ryan Sampson, later joined the attack and stabbed Mr Callahan multiple times in the back and neck.

These allegations remain matters before the courts for those defendants who have pleaded not guilty.

Ryan Sampson has pleaded not guilty to murder and to using an offensive weapon in company to commit an indictable offence.

Police allege he was one of the principal attackers during the fatal assault.

His matter has been committed to the Supreme Court, where a trial timetable is expected to be established.

Three other accused—Frank Allen, Jason Talbot and George Fernando—have also entered pleas of not guilty to murder.

Dianne Fernando has pleaded not guilty to a charge of murder as a principal in the second degree.

Because each has denied the allegations, their criminal responsibility has not been determined and will be decided during future court proceedings.

A seventh accused, Teelah Cooper, faces a separate allegation of being an accessory after the fact to murder.

Prosecutors allege she assisted Ryan Sampson after the attack and helped him avoid police.

Her matter remains before the courts, and no plea has yet been entered because aspects of the prosecution case remain disputed.

Court proceedings have previously heard allegations that Cooper later breached bail conditions by making hundreds of telephone calls to Sampson despite being prohibited from contacting co-accused persons.

Although her bail was temporarily revoked, the Supreme Court later granted her bail again under strict conditions after considering factors including her community ties, lack of prior criminal history and personal circumstances.

Those proceedings relate to bail administration rather than the determination of guilt.

The case has attracted widespread public attention because of both the apparent trigger for the confrontation and the scale of the alleged attack.

Investigators have previously described the assault as coordinated, alleging the group pursued Mr Callahan after the initial disagreement before attacking him minutes later.

Court documents released during earlier proceedings alleged there was “a level of planning and coordination” involving multiple vehicles travelling together before the confrontation. >

Mr Callahan suffered multiple stab wounds during the incident.

Emergency services treated him at the scene before transporting him to hospital, where he later died despite medical efforts to save his life.

Family members have previously described Mr Callahan as a passionate fisherman and environmentalist who cared deeply about nature and his local community.

More than one hundred people attended a memorial held at Stockton Breakwall following his death.

His mother, Sally Callahan, publicly expressed her inability to understand why her son had been targeted, saying the family continued struggling to comprehend the tragedy.

Legal experts note that Briggs’ guilty plea means the prosecution will no longer need to prove her criminal responsibility at trial.

Instead, the Supreme Court sentencing process will consider matters including the seriousness of the offending, any mitigating or aggravating factors and submissions from both prosecutors and defence counsel before sentence is imposed.

Her plea does not affect the legal presumption of innocence applying to the remaining accused, each of whom continues to deny the allegations.

Those defendants remain entitled to have their cases determined by the courts based solely on the evidence presented during trial.

As the criminal proceedings continue, the case remains one of the most closely watched homicide prosecutions in New South Wales.

The forthcoming Supreme Court hearings will determine sentencing for Briggs while separately establishing trial dates for the remaining defendants, ensuring each allegation is examined through the ordinary judicial process.