Five-hundred cows stolen from a mid-Canterbury dairy farm were probably rustled over a period of months, police believe.
Police continue to investigate the "complex" theft from the Ashburton farm property, which was reported last month.
The cows could be worth as much as $1m.
Senior Sergeant Scott Banfield said investigators have "spoken to and interviewed numerous persons" that may or may not be connected.
"Our inquiry has established that although not impossible, it is highly unlikely that a large number of cattle have been removed over a short period of time," he said.