Three men will re-appear in a Tongan court today in connection with the death of New Zealand police officer Kali Fungavaka.
Tonga's acting police commissioner, Soakai Motu'apuaka, says more evidence has been found and new charges will be made against the accused shortly.
Two of the accused are Tongan officers and both have already been charged with common assault.
Mr Fungavaka died in a Nuku'alofa hospital last Thursday.
He had been assaulted in a Tongan police cell after being arrested on a minor drunkeness charge.
Mr Fungavaka's body was flown back to New Zealand over the weekend.
Radio Tonga reports the Ministry of Police has admitted the death of Mr Fungavaka while under their care is a tragedy.
Mr Motu'apuaka also wanted to assure the nation that Tongan Police are doing their utmost to ensure the culprits are brought to justice.
He added there will be no favouritism, and the law will be equally applied to everyone.