The ginger cat’s body was discovered in the park between Roberts Crescent and Knapping Hill in the town on Sunday.
His tail and right ear were missing and vets believe they had been deliberately severed.
The cat, called Max, had been missing for 10 months. His owners, who had resigned themselves to never seeing their pet again, were left horrified after learning what had happened to him.
Police say they want to hear from anyone who has information about the attack or who knows where the cat was while he was missing.
Max had white paws, long white ‘socks’ on his back legs and a white patch on his chest.
Anyone with information is asked to call North Yorkshire Police on the force’s 101 number or to e-mail [email protected]
Information can also be passed anonymously to Crimestoppers on 0800 555111.