John Leather was a Texas Ranger in the 19th Century, along with his brother Paul. They were respected lawmen and,more importantly, had been left a valuable silver mine by their father when he died.
The Dowling Gang wanted the location of the mine. They tortured the Leather brothers for its location, which they never gave up. Paul was killed, but John managed to escape.
Half-dead, he crawled through the wilderness of Texas. His life was saved by a Native American, a Potowatomi shaman. The shaman wasn't eager to help the injured man, but couldn't simply leave him. So he decided to test John Leather. He fed him an unknown mixture of shamanic herbs, which sent John Leather into a deep trance.
When he awoke, the shaman bandaged his wounds, and the two made their way to the silver mine, where John began plotting his revenge against the Dowling gang. He cast bullets from silver, and gave each one a mercury tip. He painted a mask around his eyes, and went hunting for the Dowling Gang. Every man he shot died, either from the bullet or from the mercury poisoning, adding to the quickly growing legend of the Dead Ranger. He also apparently had the power to appear, disappear and teleport in a cloud of black, ashy, smoke.
He went on to fight lawlessness all over Texas. Eventually, however, he met a woman, fell in love and hung up his guns. On January 1st, 1900, he and his wife had a son, Bret. When John Leather died, the silver mine - and the family inheritance of wealth and a thirst for justice - passed to his son.