Shipman killed himself in Wakefield Prison in 2004
A collection of letters written by the serial killer Harold Shipman are to be sold at auction.
The 65 letters give an insight into the thoughts of the doctor, from Hyde, Greater Manchester, who was thought to have killed up to 250 patients.
They include frequent denials of his guilt and span a period from his arrest until a month before his suicide.
Nick Hall, of Frank Marshall and Co auctioneers, believes the offer a "fascinating" glimpse into his psyche.
Shipman went undetected as he killed his elderly patients in and around Hyde, certifying their deaths as natural causes.
He was convicted of 15 counts of murder but an inquiry chaired by Dame Janet Smith found he killed an estimated 215 people between 1971 and 1998.
Mr Hall said: "This is an amazing discovery which represents the private thoughts of a man behind one of the most notorious episodes in British, if not world wide, criminal history.
"Letters from Harold Shipman have been published before but none as extensive or detailed as these.
"They cover his life from his arrest to his eventual suicide and are a fascinating glimpse into what this man was thinking."
Despite Shipman's denials of guilty, Mr Hall said the letters offered an insight into his fragile state of mind.
"He slipped into a depression and he makes mention of that as well," he told BBC News.
"I think he took medication for it and he certainly saw a psychologist on his ward, as the time rolled on he was not handling things as well. His ramblings definitely became more eccentric.
"Harold Shipman was a reviled and evil man. Without a shadow of a doubt, it will evoke a lot of bad feelings about the letters."
The correspondence, which is mainly handwritten, was discovered by chance during a house clearance in 2006.
They were written to David and Mavis Stott, friends and patients of Shipman.
He began writing to the pair shortly after his arrest in September 1998 up until one month before his death in Wakefield Prison in 2004.
The collection will be sold on 10 November.