Signed and Dated Sir Arthur Conan Doyle Letter About The Murderer Oscar Slater Case August 1912

From an open source on the Internet:
"Oscar Joseph Slater (8 January 1872 – 31 January 1948) was a victim of Scottish miscarriage of justice. He was born Oscar Leschziner in Oppeln, Upper Silesia, Germany to a Jewish family. Around 1893, to evade military service, he moved to London, where he worked as a bookmaker using various names, including Anderson, before settling on Slater for official purposes. He was prosecuted for malicious wounding in 1896 and assault in 1897 but was acquitted in both cases.
In 1899 he moved to Edinburgh and by 1901 was living in Glasgow. He claimed to be a gymnastics instructor, a dentist, and a dealer in precious stones but was known to police as a pimp and gangster who associated with thieves, burglars, and receivers of stolen goods."

In 1909 Slater was found guilty of the murder of Marion Gilchrist and sentenced to death and two days before he was scheduled to die, Slater's sentence was changed to imprisonment with hard labor for life.
In 1912 Conan Doyle published The Case of Oscar Slater. It examined evidence brought forward at the trial and point by point proved that Slater was not the killer.

Please see the photos of this document, dated August 1912.

NOTE:
This item comes from a private estate who is the wife of Owner of the document. This person was a well noted collector in the field of Signatures and Documents.
The letter is from Doyle with the Rare full Signature as well as on is person Letterhead