On the evening of Good Friday, April 14, 1865, actor and confederate sympathizer John Wilkes Booth assassinated President Lincoln with a single shot to the back of the head. Few know that the person who killed Booth for his deed was an eccentric former hat maker from Troy, Thomas P. Corbett. Corbett was born in England in 1832 and came to New York with his family in 1839, finally settling in Troy where he became a hatter.

Mercury compounds were commonly used in felt hat making to kill bacteria and prevent rotting. Hatters developed the "shakes" and became unstable by breathing in mercury fumes and getting it on their hands, hence the term "Mad as a Hatter." Symptoms of chronic mercury exposure on the nervous system include increased excitability, attention/concentration deficits, mental instability, tendency to weep, fine tremors of the hands and feet, depression, hallucinations, and other personality changes. Most writers attribute Corbett's later bizarre personality to having Mad Hatter's disease.

Corbett married but his wife died in childbirth. He moved to Albany, Boston, Richmond and New York City, where he enlisted in the NYS militia. While in Boston, he changed his name to "Boston," after being converted to Methodism. Trying to imitate Jesus, he grew his hair very long and in order to avoid the temptation of prostitutes, took a pair of scissors on July 16, 1858 and castrated himself. Corbett's religious zealous behavior landed him in trouble many times when he would brandish his revolver, sometimes discharging it, at people who blasphemed the Lord in his eyes.

Corbett showed remarkable marksmanship and bravery and reenlisted three times during the Civil War. He was with a detachment of the NY 16th when surrounded by the famous "Gray Ghost," confederate Colonel John Singleton Mosby. All surrendered except Corbett who stood out and fired all of his bullets from a pistol and rifle before he finally was forced to surrender. As admiration for his bravery, Mosby ordered his men not to kill Corbett. While at Andersonville prison, Corbett tried to escape but was caught. Of the 14 prisoners, only Corbett and one other survived the imprisonment.

Corbett became Sergeant and was one of the 26 cavalryman selected from the 16th NY regiment on April 24,1865 to pursue Booth after Lincoln's assassination. On April 26, they cornered Booth and accomplice David Herold in a tobacco barn on the Virginia farm of Richard Garrett. The directive from command was "Don't shoot Booth, but take him alive."

The barn was set on fire, Herold surrendered, but Booth remained inside. According to Lt Edward P. Doherty, Corbett "asked permission to enter the barn alone, which I refused." Instead Corbett went around to the back of the barn. When he saw Booth through a crack in the barn, he took his Colt revolver from a distance of a few yards and shot Booth "on the back of his head, very nearly in the same part where his own ball had struck the President," according to Brig Gen Henry L Burnett. Booth was paralyzed and died a few hours later. Corbett disobeyed orders, proclaiming, "God Almighty directed me," and was arrested and thrown into the brig. Charges were dropped by Secretary of War Edwin Stanton, proclaiming, "The rebel is dead. The patriot lives." Corbett received his share of the reward money ($1,653.85). In his official statement of May 1, 1865, Corbett claimed he shot Booth because he thought he was getting ready to use his weapons.

Corbett returned to hat making but then moved to Concordia, Kansas in 1878 where he lived in a self-made dirt dugout a few miles out of town. He gave sermons to local churches, but brought his gun out when he felt someone wasn't obeying the lord's wishes. There are many published examples of his eccentric behavior. In 1887, he was appointed assistant doorkeeper of the Kansas House of Representatives in Topeka, but on Tuesday, February 15, after overhearing a conversation in which the legislature's opening prayer was being mocked, he jumped up, whipped out his revolver, and waved or discharged his gun. No one was injured, but he was arrested, declared nuts, and sent to the Topeka Asylum for the Insane. On May 26, 1888, he jumped on a horse left at the entrance to the asylum's grounds and escaped to Neodesha, KS, to Richard Thatcher, the other survivor of the Andersonville prison. Stating he was headed for Mexico, he instructed Thatcher to return the horse to its rightful owner. Some stories say he ended up a medicine salesman, or died in the 1894 Great Hinckley (Mn) Forest Fire. Corbett was never seen again. Four of the 8 captured Booth accomplices were hung, including the first women ever executed by the federal government.