Chilling letters written by John Lennon's killer are set to be sold off.

Mark David Chapman, the man who fatally shot the Beatles star in New York in 1980, is currently in prison serving out a sentence of 20 years to life and it has now emerged he wrote a number of letters to one of the police officers who arrested him.

New York City cop Stephen Spiro received four notes from Chapman from behind bars between January and May 1983, and he is now selling off the messages to raise funds for a local charity.

In the letters, Chapman writes about Lennon's murder and attempts to track down a copy of his favourite book, J.D. Salinger's The Catcher in the Rye, which was taken from him after his arrest.

He also urges Spiro to read the novel as he insists it "will help you to further understand (the crime)".

Spiro says of the sale, "They've been in my possession for 30 years, and I'm 66 years old, and I'm saying, you know, what am I going to do with these things? So I figured I'd sell them."

The letters will be on sale from next Monday (25Feb13) for $75,000 (£46,875). A portion of the proceeds will be donated to a shelter for battered women.