It is arguably the most famous story in the history of art: Vincent van Gogh lopping off part of his ear in a moment of insanity and dropping it off at his local brothel. But the true story of how the artist mutilated himself, and what happened next, can now be told for the first time, say experts, following the discovery of crucial medical evidence.A letter from Van Gogh's doctor, Felix Rey, shows how the artist did not cut just a section of his ear off, but had severed the whole thing in one go.The woman he delivered it to was not a prostitute, as was previously believed, but a humble maid who had been injured by a dog bite and worked to pay off her expensive treatment.Bernadette Murphy, the researcher who discovered the letter and traced the family of the unknown girl, has now speculated Van Gogh could have been offering his own flesh in a noble but deluded attempt to help heal her.The new research, unveiled at the Van Gogh Museum in Amsterdam today, is to be revealed to the public for the first time as part of a new exhibition reflecting the artist's mental illness and his eventual suicide.Murphy will also publish an accompanying book of her findings, titled: Van Gogh's Ear: The True Story, the basis of a BBC documentary later this year.The findings refer to the mythologised "ear incident" in December 1888 in the southern French town of Arles, which was well-documented by newspaper reports and eyewitnesses, including police and fellow artists.But mystery has endured regarding key details, with disputes about how much of Van Gogh's ear was damaged, and why he delivered the mutilated flesh to a girl named Rachel at a local brothel.The young woman was recorded as having fainted at the sight of the bloody ear. Many assumed she was a prostitute Van Gogh had known.Murphy, 58, has spent seven years cross-referencing limited records from the period to find the girl, eventually identifying her as a young woman named Gabrielle, who had been savaged by a dog with rabies the previous year.To pay off medical bills, Murphy found, she took a job as a cleaner at the brothel, and is likely to have been well known to Van Gogh in the small community. ..