The letter that led to police deciding to dig up a garden at the former home of a jailed paedophile in the hunt for human remains was passed to detectives a year ago, it was revealed last night.
The document alleged that remains dating back more than 30 years were buried at the property on the New Addington Estate in Croydon, south London, where pensioner Leslie Ford-Thrussell used to live.
Detectives revealed last night that they had found some "additional evidence" and "other information" to support the claims contained in the anonymous letter.
A number of factors had prevented them acting on its contents sooner, including the length of time it took to identify the author, they said.
The writer has now been identified and is being treated as a potential witness, however no one, including Ford-Thrussell, has been interviewed under caution in connection with the investigation. Missing person files from 35 years ago have been checked but detectives have found no link to anyone from the house.
The property, 107 Walton Green, is being treated as a potential crime scene.
A phased forensic examination of both the house and the gardens will begin "in the very near future", starting with a fingertip search today.
Forensic archaeologists will be consulted and specialist equipment utilised in an initial survey of the plot before officers excavate parts of the property in the privacy of a forensics tent.
Ford-Thrussell, a 72-year-old former gardener, was not living at the house 35 years ago at the time of the "historic incidents" referred to in the letter.
He lived there for 17 years before being jailed in 2004 for abusing children, although it is thought detectives are investigating whether he had any links to the property before then.