The carcasses of 11 sheep have been found on a farm in Oxfordshire.
The animals were discovered between 30 June and 24 July by the landowner whose sheep had gone missing in Barford St John, near Banbury.
PC Suzanne Goodman, from Thames Valley Police, described the discoveries as "very distressing" for the farmer.
According to police, the animals were slaughtered and skilfully butchered before their meat was removed and their carcasses left behind.
Officers want to speak to anyone who witnessed anything suspicious around the nearby airfield at Barford St John.
They have also appealed for anyone who had been offered cheap lamb to come forward.
PC Goodman said: "I would advise anyone to report this to the police and not buy or eat such meat as there could be a health risk."