Police in Thurston County, Washington, confirmed that yet another cat was found mutilated outside this week, bringing the total of dead cats to 13.

KING-TV reported that police discovered the 12th cat on Monday in Olympia on the 3800 block of Pacific Avenue after receiving reports of a cat found brutally slaughtered. Now, the Thurston County Sheriff’s Office said an additional desecrated feline was located Thursday outside in Lacey.

Animal cruelty investigator Erika Johnson told KING-TV that all the cats were likely killed during overnight hours between 11 p.m. and 6 a.m. and dumped in places viewable by the public. The news station noted that all the slain cats have been found in Tumwater, Lacey, and Olympia. It’s currently unclear whether the 14th case of a cat found dead in Port Angeles is connected to the other 13 cases.

The man who found the 13th mutilated cat, Dan Brainlee, is not the cat’s owner, according to Thurston County Sheriff’s Detective Ben Elkins.

Speaking with KCPQ, Brainlee recalled seeing a “lump” on his front lawn outside his home on Thursday night. Upon further inspection, he said he realized the lump was a cat with a flea collar on—and “a lot of the insides was gone.”

“If someone’s this twisted, there’s no way to know what they’re going to do.”

Elkins noted that the culprit typically cuts the cats open and removes their spine and/or other entrails. This cat was no exception.

The unsolved cat killings started in February, according to Pasado’s Safe Haven, the non-profit organization that’s offering a $36,000 reward in this case. While Thurston County Animal Services is leading the investigation, KCPQ said multiple agencies are working to solve this case.

With no suspect in custody, police have asked residents in Thurston County to keep their cats indoors.

[Featured image: KING-TV video screengrab (YouTube)]