Police say they have solved the M25 cat killer mystery.

Officers believe after three years of investigation, it is foxes behind the savage mutilation of cats and other pets but they believe the animals were most likely to be dead already before they were torn apart.

Up to 500 pets have been found mutilated with their heads and tails ripped from their bodies - and there were fears it was the work of a serial cat killer.

Police and campaigners have thrown plenty into finding the culprit but investigating officers were never able to find any evidence of human involvement or find CCTV.

Mutilated cats have been found dead in places in and around the M25, but there have also been reports nationwide.

Two-year-old Chewy's dismembered body was found in Oxhey Woods, Watford in January 2017 while 18-year-old Jack was found decapitated in a front garden in St Albans in May 2017.

Two rabbits in Watford were also believed to have fallen victim to the M25 cat killer.

In September 2017, a 17-year-old cat was found beheaded in its owner’s garden in Walthamstow while in November, the body of a black and white kitten, around four months old, was found by a teenage girl in Normanshire Drive, in Chingford.

The animal was beheaded with a “clean cut”, a trademark of the serial killer linked to almost 170 slaughtered cats.

Police worked with the RSPCA and the South Norwood Animal Rescue League (SNARL) from the outset but could find no evidence the cats were being killed by a human.

In 2016, SNARL arranged 25 post-mortem examinations on cats that had been found mutilated. The cause of death was found to be blunt force trauma, such as collisions with vehicles. The mutilations were found to have occurred after death, and some of these were thought to have been caused by a sharp implement.

On the basis of these examinations, six cases of cat mutilation were deemed suspicious. Officers in Croydon collated over 400 additional reports made to the Met by members of the public or animal charities of cat mutilations across London and surrounding counties.

The investigation took almost three years, due to the number of reports and allegations received from the public and the need to work with specialists to scrutinise any evidence.

No evidence of human involvement was found in any of the reported cases. In three instances where CCTV was obtained, footage showed foxes carrying bodies or body-parts of cats.

It has left police with no option but to conclude that it is the work of wildlife which are causing the deaths of the cats.

A Metropolitan Police spokesman said: “Following a thorough examination of the available evidence, officers working alongside experts have concluded that hundreds of reported cat mutilations in Croydon and elsewhere were not carried out by a human and are likely to be the result of predation or scavenging by wildlife.”