A cat owner was left distraught after one of her missing pets was found mutilated on Thursday.

Sonja Sanders of Canterbury, England, was desperately searching for her 13-week-old kittens, Hershey and Shouty, after they went missing Saturday. On Thursday night, she received a call that Hershey was found mutilated.

“They were as thick as thieves and they went together. We left a window open and they got out -- the guilt that comes with this is overwhelming. These kittens weren't independent, they were so stupid, bless them. They didn't understand the outside. They were my babies and one of them is still out there. Shouty is still missing and I can't help but think the worst,” Sanders said.

Recalling the moment when she was informed that Hershey was found mutilated, Sanders said, "Someone saw my relentless social media posts and asked me to call her and she told me she'd found a piece of him. People are saying it's a fox or another animal and that's what I was hoping for as it might have been a quick death, but it was a mutilation. From his ears, from behind, his face was completely cut off. I haven't seen a picture because it's too upsetting.”

Calling the case “suspicious,” The South Norwood Animal Rescue and Liberty (SNARL), an organization that investigates cases of animal mutilations, said it was likely done by a person.

"From the injuries described it sounds very much like it was caused by a bladed instrument and not an animal attack,” a spokeswoman said, adding that a police complaint has been filed.

A police spokesperson said, “Police received a report that a cat missing from an address in Hollow Lane, Canterbury, had been found dead by a member of public. The cause of the cat’s injuries are not known at this stage and enquiries are ongoing."

Meanwhile, there was no information about Shouty as of Friday.

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In this image, a cat lounges next to a window at The Cat House on the Kings in Parlier, California, Aug. 25, 2017. Justin Sullivan/Getty Images