A dead sheep from Tilgate Park Nature Centre was found burned in the woods.
Police suspect the sheep was taken from its paddock and attacked by a dog overnight before it was found on Thursday morning (October 16).
A spokesman for Sussex Police said: “This is a horrendous incident and we would appeal to anyone who has information to contact us.
“The centre has reported on-going incidents of sheep worrying and we are looking into this.”
Anyone with information was asked to contact police on email@example.com, call 101 or the independent charity Crimestoppers anonymously on 0800 555 111.