The amateur sleuths who have come to be known as the "ripperologists" will have been closely following events at New Scotland Yard today.
The family of the chief investigating officer of the Jack the Ripper killings of 1888 were there to give an "open loan" to the Metropolitan police of some of his handwritten notes.
In them, Donald Sutherland Swanson outlines some of his thoughts about the killer's identity. He was convinced the man who is thought to have murdered and mutilated at least five prostitutes in Whitechapel in east London was Aaron Kosminski, who was a serious suspect during the investigation.
A possible witness of the killer after one of the murders is believed to have implicated Kosminski, a Polish Jew with psychiatric problems. The witness, however, did not want to formally give evidence, possibly because they were also Jewish.
In a book, Swanson wrote notes in the margins that Kosminski was the man seen by the witness. Kosminski was never charged but was bundled off to an insane asylum and is said to have died in 1919. Many ripperologists have dismissed the Kosminski theory; although others think he should be reconsidered.
Swanson's notes are in a book written by one of Swanson's superiors, Assistant Commissioner Robert Anderson, who wrote it during his retirement.
The book will go into Scotland Yard's crime museum, which is - unfortunately - not open to the public and used to help train police officers. The museum was reopened today after being spruced up for the multi-media age.
The identity of Jack the Ripper has, of course, never been proven and there is a dizzying array of people who have been named as possible suspects over the years. As an indication of how many names have been touted, a page on the Wikipedia online encyclopaedia mentions 24 suspects, of varying plausibility.
Because of the way the victims were mutilated, a popular theory was that the killer had some medical background or was a butcher. There have also been a number of royal ripper theories linking Prince Albert or his associates to the killings, though none of these are given great support by the ripperologists.
One author, Richard Wallace, claimed Lewis Carroll was a suspect because, Wallace claimed, there were anagrams about the murders in his books, including Alice in Wonderland. Nobody has taken this theory very seriously.
Sir Arthur Conan Doyle was among those who speculated over the Jill the Ripper theory, which suggested the killer was a woman, possibly a midwife, or posed as one, so as not to arouse suspicion by having bloody clothing.
One thing that is certain is that the crimes continue to fascinate almost 120 years since a shadowy figure stalked the streets of Whitechapel looking for victims. If you put "Jack the Ripper" into Google you get 6.25 million hits, which is only 3 million less than Wayne Rooney.
The curators at the crime museum are very pleased to have been loaned the book with the notes, the existence of which emerged in 1981.
The book will join an impressive number of artefacts relating to famous criminals. The museum was first opened at the original Scotland Yard in 1875 and has material relating to the Krays, Dr Krippen and the Great Train Robbery.
