Two other arrests have been made by police in relation to the man's death, and while the main offenders have been charged, Detective Inspector Darrell Harpur is confident it won't be the last.
Police also extended their sympathies to Tongia's loved ones.
"I want to acknowledge the investigation team who worked tirelessly on this very complex case, and commend them on their professionalism and dedication to holding those involved to account. They worked long hours and took valuable time away from family throughout the holiday period to ensure justice was done for Rau Tongia."
The two women already charged in connection with the death have been granted interim name suppression.
A 20-year-old woman, who is accused of being an accessory to Tongia's murder on December 20, grinned and mouthed words to her supporters as she stood in the dock at the Wellington District Court on Thursday 21 January.
A 35-year-old woman charged with murdering Tongia also appeared in court last Thursday.
Court documents allege the younger women "actively suppressed evidence" by hiding a firearm at an associate's property to help someone avoid conviction.
Police revealed last week they had found a firearm during a search in Wilton that they believed was linked to Tongia's death. It is being forensically analysed.
Police said they are also looking into whether the weapon is linked to other offending across the district.
