Tonga's acting police commissioner, Siopesoaki Motu'apuaka, says the death of a New Zealand police officer after he was assaulted in custody is a shock.
Kali Fungavaka was assaulted while in a police cell last Saturday and died last evening at Vaiola Hospital in Nuku'alofa.
He had been in Tonga attending the funeral of his grandfather and was arrested on a minor drunkenness offence late last Friday.
A prisoner who allegedly committed the assault has been arrested while two Tongan Police staff have also been arrested for an earlier attack on Mr Fungavaka.
Acting commissioner Motu'apuaka says finding out what happened is a priority for local police.
"That's our most priority in the Tonga police is to address this case, nothing else"
Siopesoaki Motu'apuaka says Tonga's prime minister and senior police officers have visited Mr Fungavaka's widow to pay their respects.