Hayden Burt, Aaron Boden and siblings Cody and Korina Boyes had been on trial in the High Court at Christchurch since late September.
Moana, 37, disappeared in December 2021 and his body has never been found, despite extensive police efforts.
On Thursday, the jury delivered unanimous guilty verdicts for Burt, Boden and Cody Boyes before Justice Gordon.
Burt and Boden were also found guilty of kidnapping and injuring with intent.
Korina Boden was found not guilty of murder and the lesser alternative charge of manslaughter, but guilty of injuring with intent.
A fifth person, Joseph Cropley, was found not guilty of kidnapping and injuring with intent.
The Crown argued Moana was lured to the Kelceys Bush reserve near Waimate and ambushed, the supposed victim of a revenge attack.
Prosecutor Shawn McManus said Moana fled for his life and climbed a tree in the reserve.
Two shots were fired at Moana in the tree, when he fell and was attacked on the ground.
The attack was thought to be retribution after Moana and an associate stole a large quantity of methamphetamine and cash worth about $60,000 from a car in Oamaru three months previously.
Jurors heard how Moana's associate and former roommate Heremaia Repia-King was left "battered, bruised and bleeding" after a group of men violently attacked him over the theft.
Now in custody, Repia-King was called as a Crown witness and told the court how he sustained small stab wounds on his forearm and thigh, after one of the attackers took his Stanley knife.
Repia-King was warned he owed $60,000 and had 16 weeks to pay up.
The group will be sentenced on December 17.
