Farmers have been warned to keep an eye on their livestock after at least 45 lambs and sheep were “professionally slaughtered” in fields within the space of a week.
In the last week there have been four brutal attacks on livestock across Northamptonshire, all within 30 miles of one another.
Many of the animals were killed and stolen, but several carcasses were left for farmers to discover.
Police believe the spate of butchery began last Sunday when 14 lambs were killed between 4pm on Sunday and Monday afternoon.
The carcasses of 12 lambs were stolen, with the remains of two others left in the farmer’s field near West Haddon, Northamptonshire.
In the village of Whilton, near Daventry, 21 lambs were killed and then stolen at some point between the early hours of Tuesday morning and Wednesday morning.
The butchered remains of at least 10 sheep were later discovered on Saturday morning in a field in Kelmarsh, and in nearby Moulton a lamb was found tied up with the wire from an electric fence.
Northamptonshire Police is now warning farmers to remove loose fencing or farm equipment and to watch out for suspicious activity.
Inspector Scott Little said: “To have this many incidents in just a few days is extremely concerning and we are appealing for information from the rural community to help us catch those responsible.
“The lambs appear to have been professionally slaughtered and their carcasses have then been stolen.
“For farmers to find their animals have been killed and butchered like this is not only very upsetting, it also has financial repercussions.”
Police will visit farmers and other landowners over the next few days as part of their inquiries.
Mr Little added: “If you suspect someone has attempted to target your animals or find that you’ve lost livestock in this way, please report it to the police immediately.”
Press Association contributed to this report.