The heads of 19 deer have been discovered in a field off Brampton Lane near to the A508 in Chapel Brampton, near Northampton.
The remains, possibly from fallow deer and in varying states of decomposition, are believed to have been dumped there in the past two months.
Police would like to hear from anybody who has seen anything suspicious over recent weeks in the area the heads were discovered, or been offered cheap venison for sale.
Restaurant and pub owners are reminded they should be able to provide a paper trail to show where they sourced their venison if they are offering it on their menus and are warned against purchasing illegally gained meat from poachers.
The law states that it is an offence without the consent of an authorised person to: 1(a) to enter any land in search or pursuit of deer with the intention of taking, killing or injuring it, or 1(b) while on any land to intentionally: take, kill or injure any deer or attempt to do so, or search for or pursue deer with such intent, or remove the carcass of any deer.
Witnesses to the incident, or anyone with information, are asked to call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.