Affected by delusions, he shot a man who he believed had broken into his room, and was consequently committed from 1872 to 1910 to a secure British psychiatric hospital.

He was one of the project's most effective volunteers, reading through his large personal library of antiquarian books and compiling quotations that illustrated how particular words were used.

On February 17, 1872, haunted by his paranoia, he fatally shot George Merrett, whom Minor wrongly believed to have broken into his room.

After a pre-trial period spent in London's Horsemonger Lane Gaol, Minor was found not guilty by reason of insanity and incarcerated at the asylum in Broadmoor in the village of Crowthorne, Berkshire.

[13] He became one of the project's most effective volunteers, reading through his large personal library of antiquarian books and compiling quotations that illustrated the way particular words were used.

In 1899, Murray paid compliment to Minor's enormous contributions to the dictionary, stating, "we could easily illustrate the last four centuries from his quotations alone".

In 1902, he was suffering delusions that he was being abducted nightly from his rooms and conveyed to such distant places as Istanbul, where he was forced to commit sexual assaults on children.

[16] His health continued to worsen and, after Murray campaigned on his behalf, Minor was released in 1910 on the orders of the then Home Secretary, 35 year-old Winston Churchill.

[17] In July 1915, the Washington D.C. Sunday Star published a "sensationalized" story beginning with the line "American Murderer Helped Write Oxford Dictionary".

A movie based on the book, called The Professor and the Madman, starring Mel Gibson as Murray and Sean Penn as Minor, was released in May 2019.