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Johnson is said to have been born near Little York, New Jersey,[original research?][dubious ] with the last name Garrison.[dubious ][original research?] During the Mexican-American war he served aboard a fighting ship, having enlisted under a false age. After striking an officer, he deserted, changed his name to John Johnston, and traveled west to try his hand at the gold diggings in Alder Gulch, Montana Territory. He also became a "woodhawk," supplying cord wood to steamboats. He was described as a large man, standing about six foot two inches in stocking feet and weighing in the area of 260 pounds with almost no body fat.
Rumors, legends, and campfire tales abound about Johnson. Perhaps chief among them is this one: In 1847, his wife, a member of the Flathead American Indian tribe, was killed by a young Crow brave and his fellow hunters, which prompted Johnson to embark on a vendetta against the tribe. The legend says that he would cut out and eat the liver of each man killed.[dubious ] This was an insult to Crow because the Crow believed the liver to be vital if one was to go on to the afterlife. In any case, he eventually became known as "Liver-Eating Johnson". The story of how he got his name was written down by a diarist at the time. There were three Johnsons, nicknames were commonplace, and with Johnson's show of eating the liver, he received his name.
One tale ascribed to Johnson (while other sources ascribe it to Boone Helm) was of being ambushed by a group of Blackfoot warriors in the dead of winter on a foray to sell whiskey to his Flathead kin, a trip that would have been over five hundred miles (805 kilometers). The Blackfoot planned to sell him to the Crow, his mortal enemies, for a handsome price.[vague] He was stripped to the waist, tied with leather thongs and put in a teepee with only one, very inexperienced guard. Johnson managed to break through the straps, then knocked out his young guard with a kick, took his knife and scalped him, then quickly cut off one of his legs.[dubious ] He made his escape into the woods, surviving by eating the Blackfoot's leg, until he reached the cabin of Del Que, his trapping partner, a journey of about two hundred miles (322 Kilometers).
Eventually, Johnson made peace with the Crow, who became "his brothers", and his personal vendetta against them finally ended after twenty-five years and scores of Crow warriors had fallen. The West, however, was still a very violent and territorial place, particularly during the Plains Indian Wars of the mid-19th century. Many more Indians of different tribes, especially but not limited to the Sioux and the Blackfoot, would know the wrath of "Dapiek Absaroka" Crow killer and his fellow mountain men. 
The above information is based upon the yarns and tales told over and over through the years. The novel Mountain Man by Vardis Fisher is a good fiction source. The accurate story is told in the diaries of Lee and Kaiser who were on the Missouri River in 1868 when Johnston was given his moniker, after a rainy fight with the Sioux.
He joined the Union Army in St. Louis in 1864 (Company H, 2nd Colorado Cavalry) as a private, and was honorably discharged the following year. During the 1880s he was appointed deputy sheriff in Coulson, Montana, and a town marshal in Red Lodge, Montana. He was listed as five foot, eleven and three-quarter inches (1.82 meters) tall according to government records.
In his time, he was a sailor, scout, soldier, gold-seeker, hunter, trapper, whiskey-peddler, guide, deputy, constable, builder of log cabins, taking advantage of any source of income-producing labor he could find.
His final residence was in a veterans' home in Santa Monica, California. He was there for exactly one month before dying on January 21, 1900. His body was buried in a Los Angeles veteran's cemetery. However, after a six-month campaign led by 25 seventh grade students and their teacher, Johnson's body was relocated to Cody, Wyoming in June 1974.
- Crow Killer: the Saga of Liver-Eating Johnson by Raymond W. Thorp and Robert Bunker (1958) Indiana University Press, Bloomington, Library of Congress catalog card number: 58-8120 (a possible later version/printing (1969) ISBN 0-253-20312-0) The annotated biography, compiled from interviews with people who had actually known Johnson, with footnotes
- Jeremiah Johnson, a 1972 film by Sydney Pollack starring Robert Redford
- John Johnston, Felton & Fowler's Famous Americans You Never Knew Existed, By Bruce Felton and Mark Fowler, Stein and Day, 1979 ISBN 978-0-8128-2511-4
- Johnson is referred to as a character in 'Riverworld', a fictional universe and the setting for a series of science fiction books written by Philip José Farmer.
- Langford, Nathaniel Pitt (1912). Vigilante days and ways: the pioneers of the Rockies; the makers and the making. A. C. McClurg.
- "Jeremiah Johnson's Body To Be Moved". Evening Independent. Associated Press. May 28, 1974. p. 12-A. Retrieved October 20, 2013.
- Crow Killer: the Saga of Liver-Eating Johnson
- Jon Axline, "In League with the Devil: Boone Helm and 'Liver-Eatin' Johnston'," in, Still Speaking Ill of the Dead: More Jerks in Montana History, edited by Jon Axline and Jodie Foley. Guilford, Connecticut and Helena, Montana: Two Dot,Globe Pequot Press, 2005.
- Nathan E. Bender, “Perceptions of a Mountain Man: John “Jeremiah Liver-Eating” Johnston at Old Trail Town, Cody, Wyoming.” The Rocky Mountain Fur Trade Journal v.1 (2007): 93-106. Published by Museum of the Mountain Man, Pinedale, Wyoming.
- Nathan E. Bender, “The Abandoned Scout’s Revenge: Origins of the Crow Killer Saga of Liver-Eating Johnson,” Annals of Wyoming v. 78 n. 4 (Autumn 2006): 2-17. Published by the Wyoming State Historical Society.
- Nathan E. Bender, “A Hawken Rifle and Bowie Knife of John ‘Liver-Eating’ Johnson,” Arms & Armour: Journal of the Royal Armouries, v. 3 n. 2 (October 2006): 159-170.
- William T. Hamilton, "Journal of a Mountaineer" edited by Douglas W. Ellison, Western Edge Book Distributing: Medora, ND, 2010