A breakthrough has been made in the hunt for the Croydon cat killer after tests confirmed mutilated pets had died at the hands of humans, the RSPCA has claimed.

Scientific analysis of several headless cats found dumped across south London suggests the victims had been mowed down by a car before being decapitated, according to the charity.

The bodies of more than 10 felines have been found butchered in Croydon and the surrounding areas in the past five months, raising fears of a sick serial killer and prompting a police investigation.

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The RSPCA, which initially suggested foxes could be behind the deaths, post-mortem examinations conducted by specialist vets and forensic experts suggested human involvement. 

A spokesperson said: “We have been passed some bodies of cats and a series of examinations will be carried out by specialist vets and forensic experts to see if we can find out what caused these deaths. We are currently awaiting a report containing the results of those examinations.

“However, early analysis indicates that the likely cause of death was blunt force trauma, potentially consistent with being hit by a moving vehicle. 

"Examination of the bodies we have received showed that the heads and tails appear to have been removed by a human, after death.”

But South Norwood Animal Rescue and Liberty (SNARL), a shelter which initiated an investigation into the deaths and has been orchestrating efforts to protect pets, said it doubted the RSPCA's findings.

The group wrote on Facebook: "Our vet does not agree with these findings and as he has seen three times the number of bodies the RSPCA has, we are inclined to agree with him.

"Just because some of the deaths are unexplained, doesn't mean that a particular theory is appropriate to hang your hat on.

"Whilst we have nowhere near the resources the RSPCA has, we have been doing this for a fair amount longer and we need to give them the opportunity to catch up."

The cat deaths have gained widespread national media attention since first being reported in the Croydon Guardian in October.

Animal rights campaign group PETA has offered a £5,000 reward for information leading to the arrest of the person dubbed some by the "cat ripper of Croydon". 

Celebrities including Martin Clunes and Dermot O'Leary have backed calls to find the killer.

But police have few hard leads and are yet find conclusive evidence that the deaths caused by a human.

The RSPCA today appealed for any suspicious deaths to be reported.

A spokeswoman said: “Please be reassured that we take all reports of animal cruelty very seriously. A dedicated team is continuing to work closely with the police and looking into all evidence given to us to see if there is deliberate cruelty involved. 

“We are particularly keen to be called if and when a cat is found dead in suspicious circumstances so we can do all relevant tests and investigate what killed him or her.

“We would also appeal for any drivers who believe their vehicle could accidentally have hit a cat to contact the police as part of the ongoing investigation.  

Anyone with information is asked to contact the RSPCA on 0300 123 8018, Detective Sergeant Andy Collin from the Metropolitan Police on 0208 6490216 or SNARL on Facebook.