Rawlinson said the investigation into Zain’s death was ongoing.
“Police would ask anyone who may have information of value to us, to come forward.”
Police can be contacted via 105, referencing file number 250726/5566. Alternatively, information can be passed anonymously to Crime Stoppers on 0800 555 111.
Those facing a murder charge include a male youth arrested in Whanganui, and adult men from Maketū and Rotorua, ranging in age from 22 to 63.
At their first court appearances last month, all were remanded in custody without plea until September 19 when they will appear in the High Court at Tauranga.
All were granted interim name suppression until then.