The Metropolitan Police began investigating the series of incidents in November 2015, under the name Operation Takahe led by Detective Sergeant Andy Collin, after the local unregistered animal charity South Norwood Animal Rescue and Liberty (SNARL) raised concerns about a series of cats found dead and missing their heads and tails.[9] Police initially looked into whether the cats had been attacked by other animals such as foxes.[10] By February 2016, the deaths of 10 cats (four in Croydon and one each in Streatham, Mitcham Common, Sutton, Charlton, Peckham and Finchley) had been linked by an examining vet.[6] Following investigation into the mutilated remains, police believed a person or persons unknown to be responsible, and cat owners in the areas were advised not to let their cats out at night.[11]