By Tamasin Ford
Newsbeat reporter in Somerset
It's believed most of the cats were poisoned with antifreeze
Cat owners in a Somerset seaside resort are being told to keep an eye on their pets and, if possible, keep them indoors after 27 deaths in a 20-mile radius.
Local police and the RSPCA are trying to work out whether the deaths are just freak accidents or whether there's a psychopath on the loose.
The problem is, most of them were poisoned with antifreeze.
The latest was Smudge on the Bournville Road estate in Weston-super-Mare. He was found by his owner, Chris, last week.
"On Saturday he seemed fine but by Sunday he got worse," he said.
"He was having fits, rolling around in pain and by Monday morning there was no life in him whatsoever so I took him to the vets.
"They said he was in a deep state of shock and he had been poisoned."
Chris had no choice but to put Smudge to sleep: "I was devastated, it was really hard to let him go."
Less than 20 miles down the road in Bridgwater, 18 cats have been found dead.
In Weston-super-Mare, Smudge takes the total number in this area to nine.
It's thought most of them have been poisoned with antifreeze.
Cats are attracted to the sweet taste of something found in antifreeze, but if they have too much of it they only have a few hours to live unless they're treated quickly.
The cat soon becomes thirsty, tired, unsteady on its feet before it starts vomiting and then collapses. They eventually die of kidney failure.
Chris's neighbour has two cats and one of them is missing.
Even though he often takes himself off for a few days at a time, owners Andrew and Liz are a little worried.
Andrew said: "If someone is out doing something it wouldn't surprise me. In this area, would it surprise you?"
The police and the RSPCA are investigating whether these deaths are freak accidents or whether someone is maliciously poisoning cats in the area.
The Animal Welfare Act 2006 states that anyone found guilty of causing unnecessary suffering to an animal can face a maximum six-month prison sentence and a £20,000 fine.
Becky Martin works at the Green Pastures Vets in Weston. She's seen about four or five cats poisoned in the last few weeks.
She said: "The first thing that I thought was that maybe they had got hold of the poison accidently.
"But when you get nine in such a concentrated area, your mind does start to think has someone done it maliciously."
Walking around the area, there are no obvious ponds or streams which could have been infected.
Neither are there any big businesses or science labs at the local school which could be leaking any sort of chemicals into the environment.
Becky continued: "I've been practising for six years and I've never really seen one or two cases, let alone nine in total.
"If it was a leak, in my mind it would have happened at other times too, so it makes you wonder whether someone is doing this."
Becky's still waiting on the results of autopsies and blood tests but she's pretty sure she knows the cause of the deaths.
They just have no idea how it's happening or who's at fault.
"In my mind there's not really any doubt that that's what they died of but we obviously need firm evidence to pursue the investigation," she added.