BERKELEY, Calif. – For her book on Dutch artist Vincent Van Gogh’s famously mutilated ear, British author Bernadette Murphy needed to clear up confusion about the extent of the damage the artist inflicted on himself in 1888.

So she called up UC Berkeley’s Bancroft Library.

Somewhere in the archives of the late Irving Stone, author of the fictionalized Van Gogh biography Lust for Life, she suspected there lay a signed letter from Van Gogh’s doctor detailing the self-mutilation.

Then library assistant David Kessler searched through an uncatalogued box devoted to that book, and finally retrieved the note and a sketch of his left ear, which attested to the fact that the artist removed all but part of the earlobe.

That tale and more are now revealed in the newly published book “Van Gogh’s Ear: The True Story” (Chatto & Windus, London).

The letter, on loan from the Bancroft, went on display at the Van Gogh Museum on July 15 as part of an exhibit titled “On the Verge of Insanity.”

This is the first time the museum has focused specifically on the Impressionist’s much-debated mental condition.

The letter is also the centerpiece of a new BBC documentary of the same name, “Van Gogh's Ear,” that will premiere in the fall, and which is based on Murphy’s book.

David Faulds, now the Bancroft Library curator of rare Books and literary manuscripts, delivered the letter, written and signed by Dr. Félix Rey on Aug. 18, 1930, to the museum.

For more about the letter, visit https://www.vangoghmuseum.nl/en/about-the-museum/press/press-image-bank/images-on-the-verge-of-insanity/letter-from-felix-rey-to-irving-stone ; for more on the exhibit see https://www.vangoghmuseum.nl/en/about-the-museum/press/press-releases/van-goghs-illness-ear-and-suicide-explored-in-depth-for-the-first-time .