Big Mike worked as a slavetaker for Dredda Otis Trask and her people, bringing slaves to the mine at Slake City, although not freely; he himself was a slave, bound by laser manacles; they used one to amputate his right hand. When the companions escaped, they ran into him returning to the camp with a new batch of slaves. They beat him badly, but let him live, figuring letting him live with one hand was punishment enough. (Breakthrough)
They later ran into him in Idaho and inadvertently rescued him from a pack of mutie coyotes; he informed them that the Shadow Worlders were back and taking their own slaves, they had captured him, but he got free at the cost of his other hand. They dragged him along for the attack the mine, but he fled during the chaos.
In his glee at outwitting everyone, he stumbled off the road onto a section of weak glass, which collapsed, dropping him into a crevasse (Doom Helix).