Dubbed the Croydon Cat Killer or the M25 Cat Killer, the person was accused of mutilating hundreds of moggies since 2015.
Detectives were drafted in to hunt down the culprit after animal lovers suspected the culprit was a human who was going round chopping off cat’s head.
This progressed to the cats suffering more extreme mutilation.
But after a three year investigation and many hours of detective work during which the cat remains were put on ice, the Met Police said there was no evidence the felines died at the hands of a human.
Instead the injuries suffered by the cats were likely to be caused by natural predators and scavengers.
A 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.
“There was no evidence that any of the cats had been killed by a human, however media reports of a ‘Croydon Cat Killer’ or an ‘M25 Cat Killer’ led to widespread public concern about cats being harmed and subsequently many more allegations were received.”
Croydon officers began investigating the killings in November 2015 alongside the RSPCA and local charity South Norwood Animal Rescue League (SNARL).
SNARL arranged for a veterinary pathologist to carry out 25 post-mortem examinations on cats that had been found mutilated in 2016 - of which six cases were deemed to be “suspicious” by the Met.
The officers collated more than 400 reports of cat killings made in London and surrounding counties and took expert veterinary advice.
A police spokesman said: “No evidence of human involvement was found in any of the reported cases.
“There were no witnesses, no identifiable patterns and no forensic leads that pointed to human involvement.
“Witness statements were taken, but no suspect was identified.
“In three instances where CCTV was obtained, footage showed foxes carrying bodies or body-parts of cats.
“Such apparent spates of cat mutilations are not unknown in the UK and elsewhere.
“Officers were aware of a spate of reported mutilations some 20 years ago which were eventually attributed to predation by wildlife.
“However the evidence initially provided by the six post-mortem examinations warranted further investigation of the more recent spate.
“On Thursday, 20 September, Croydon officers met with SNARL and the RSPCA to set out the investigation’s final conclusion that there is no evidence of human involvement.
“All of the cases of cat mutilation will be recorded as ‘no crime’.”
Frontline Policing Commander Amanda Pearson said: “On average, the Met receives over 1,000 calls each month relating to animals and animal welfare.
“We understand the reason for this - people trust the police to help them when they suspect others have done wrong, fear for their own safety or simply are facing situations that they are unable to handle themselves.
“We will always assist the public in an emergency, but I would urge people to report concerns relating to animal welfare in the first instance to the RSPCA.
“The decision was made to allocate a large number of similar reports of mutilated cats to the officers who were investigating the initial spate of such allegations.
“In particular, they were following up the six suspicious cases identified by the post-mortem examinations.
“While this increased the workload of those officers, it significantly reduced the resources that would have been required for different officers in different units to record and assess each allegation separately.
“It is this collating of reports that enabled officers to work with experts and reach the conclusion that no further police investigations are required into any of the allegations relating to mutilated cats.”