The M25 cat killer is thought to have killed around 400 cats and small animals, leaving their maimed bodies in the open to 'horrify' people.

Police are looking for the killer, who has been labelled a 'psychopath', who kills the animals with a blunt object before cutting them with a sharp implement.

The killer was first given the moniker 'the Croydon cat killer' as the killings took place in the South London area in October 2015.

Yet in the past three years, animals in Surrey, Manchester, Sheffield and Birmingham are believed to have been killed by the cat killer.

Bertie, 12, was one of the Croydon Cat Killer's victims. His headless body was found in Surrey

The feline on the left lost her paw to the Croydon cat killer and five-month-old Storm (right) was found headless in Staines

The deaths have been logged by South Norwood Animal Rescue and Liberty (Snarl), who have been helping police with their investigations.

Tony Jenkins, Snarl co-founder, said: 'We are seeing the exact same injuries, and he leaves a signature.

'If there is more than one killer, it is likely to be a joint enterprise rather than a copycat killer.

'We suspect he gets off on hanging about and watching people's reactions. We can't prove that, but we strongly suspect it is the case because of the way he is displaying the bodies.

'It is definitely an act against humans on that basis - he leaves them underneath bedroom windows whilst he hangs around to see someone find their beloved cat decapitated.'

When quizzed what the motive of the killer may be, he said: 'I think the motive is to horrify humans. Why else would you get a fox and cut its head completely off and then place the body pointing to the children's playground not 10 metres away.

'It is definitely an attack on humans, to terrify humans.'

It is understood by Snarl that the killer is a white man in his 40s, who lives in Croydon - due to his ease operating around the suburb

Mr Jenkins added that up to 400 animals, including cats, rabbits and foxes, had been beheaded, with others having their tails severed by the attacker.

The Metropolitan Police has been working with the RSPCA and Snarl.

There has been no arrests to date and no suspects have been identified. Scotland Yard said there is no evidence that there is a risk to human life.

Detective Sergeant Andy Collin, from Croydon CID, said: 'We are investigating a number of leads, and are keeping an open mind regarding suspects, while following up different lines of enquiry.

'We are now convinced the cats are being killed then mutilated - and would be really keen to hear any relevant information from members of the public who believe they can help us.'