The 40-year-old victim went to a house in Woodville, 27km east of Palmerston North, on July 11, where he was spoken to by a woman.
He was then attacked by two men, who forced him to hand over the keys to his van and his bank card and give them the pin number. He suffered minor facial injuries including chipped teeth and bruising.
One of the men kept him at the address, where a third man was seen, while the other drove to an ATM where he withdrew cash.
Before he was released the victim was told he and his family would be harmed if he contacted police.
The man later discovered about $8500 worth of tools had been taken from his van.
Police said all four people believed to be involved were described as Maori.
They alleged the woman was Darnell Faulton Rumbal, 27, while her partner Donald Georges Keepa, 29, was also alleged to be involved.
Keepa was a patched Mongrel Mob member who was wanted for breaching his prison release conditions.
The pair had a number of associates in the area but also had contacts in Wanganui and Rotorua, police said.
