Police have searched a property as they continue investigations into the theft of hundreds of cows from an Ashburton farm.
More than 500 cows were stolen from Pennie Ormsby-Saunders' farm over a period of months.
Police on Friday searched another Ashburton property belonging to a "person of interest in the investigation", but have yet to make any arrests.
Last month, farmer Ms Ormsby-Saunders took to Facebook in an attempt to track down the missing herd.
"We have had approximately 500 cows stolen from our large dairy farm in the Ashburton area," Ms Ormsby-Saunders wrote.
"If anyone has seen or heard anything suspicious we would love to hear from you. You could also contact the Ashburton police."
Ms Ormsby-Saunders told Newshub she has a herd of 1300 cows but three weeks ago noticed more than a third of them were missing.
Police confirmed last week they would have been shifted over a period of months, rather than days.
The cows were in calf and grazing over winter, south of Ashburton.
Each cow would be worth more than $1000, meaning the stolen cattle could be worth more than $500,000 in total.
Police are urging anyone with information on the theft to contact Canterbury Police on (03) 363 7400, or anonymously call Crimestoppers on 0800 555 111.
Rick Powdrell from Federated Farmers says stock thefts are a concerning trend.
"In recent times there've been a number of thefts in that area. Now whether these are connected, we don't know.
"You have the opportunists who take the odd animal here and there, then you have what I call the professionals. These people would have to be highly organised."
He estimates the theft would have taken around 10 truck and trailer loads, and says it will be very difficult for the farmers in already stressful times.
July 10: All 1292 cows in the herd are accounted for.
Around 6 weeks later: Farmer notices extra feed and fewer calves from the herd.
August 25: Police notified of the missing cows.
August 29: Online plea by farm manager to help find missing cows.
September 8: Police reveal it would have taken months, not days, to remove cows from the herd.
September 9: Police search an address of a "person of interest".