A letter from Marilyn Monroe to her acting mentor, presumably written in the actress’s final days, is going up for auction. The undated letter, written on stationary from the Bell Air Hotel, details Monroe’s struggles and her suicidal thoughts. She eventually died from an overdose of barbiturates, but her psychological issues before the event are laid out in painful clarity in the document.

She wrote: 'My will is weak but I can't stand anything. I sound crazy but I think I'm going crazy. It's just that I get before a camera and my concentration and everything I'm trying to learn leaves me. Then I feel like I'm not existing in the human race at all.'

The letter is expected to sell for up to £33,000. It is only one of the historical documents that will be offered up for auction by the anonymous collector. This part of his collection also includes a number of letters from Dwight D. Eisenhower to his wife, in which the president shared news of the war and expressed his devotion to Mamie. There is also a typed letter from John Lennon to Paul McCartney.

The entire collection will go on sale online, however selected items will be exhibited April 8-16 at Douglas Elliman's Madison Avenue art gallery. The part of the collection to be auctioned off contains 250 items in total.

Marilyn Monroe, Dead Earners Chart
The jarring letter reveals Marilyn Monroe's struggle for sanity.