It's alleged that in August last year Kali Fungavaka was attacked by the six, in and outside the main police station, after being arrested for drunk and disorderly behaviour.
The case has attracted national attention, and is also the focus of the New Zealand's Tongan community, of which officer Fungavaka was a member.
The hearing has already heard medical evidence that the victim died after bruising and haemorrhaging to his brain, and a fractured neck bone.
Today they court has heard evidence from a prisoner in the police station who witnessed the event.
Our reporter Monalisa Palu was in court, and spoke to Pacific Correspondent Campbell Cooney after it adjourned for the day.
Presenter: Campbell Cooney
Speaker: Monalisa Palu in Tonga
PALU: The preliminary inquiry was supposed to take about three days and by the end of today, which is the third day, only 19 witnesses have been heard out of 32 for the prosecutor and the witnesses have been quite diverse with police officers and a pathologist giving evidence yesterday. But today, by the end of the day, we heard from a witnesses who is an inmate and was there the night that Kali Fungavaka was killed at the Central Police Station. He described some gruesome, in gruesome detail what happened around 12.30 when he was brought in to Nuku'alofa Police Station, right up to that to the time he had to help another inmate and a police officer take Kali Fungavaka into the van. They eventually took him to the hospital where he was pronounced dead later.
COONEY; Who was on the table for talking on Thursday?
PALU: They're going to continue with the same witness, but they say it's going to be in a smaller court room They had not just really anticipated it would take much longer and it will resume at around ten o'clock. But the testimony was heard by a houseful of family members of Kali Fungavaka who flew in as well as friends and just people who are very, very interested in what actually happened on the night.
COONEY: Is any of the accused in the court as well?
PALU; Yes, all six of them are in the court room and I had asked the civilian whether they will be testifying soon and he said, he expects either to be called tomorrow or the day after depending on how long the testimonies are. But this morning, the media were actually told not to say any of the, told by the police magistrate not to say, not to announce any of the names of the defendants, because if there is a trial, this might change the public perception of potential jurors.
COONEY; It seems to be generating plenty of interest there and also in New Zealand as well?
PALU: It is, people are following it and we notice that a lot of the family members have flown in especially for it. There's just a lot of interest, because it kind of quietened after all the publicity last year, but we expect the interest will grow as more witnesses are called.