In 2001, Mitchell crossed paths with 16-year-old Johnny Theodore Orsinger, a teenager who had been involved in the carjacking and double murder of 47-year-old David Begay and 30-year-old Jasbert Sam on August 28. In October, the two made their own plans for a carjacking and murder. On October 28, 2001, Mitchell and Orsinger were hitchhiking when they were picked up by 65-year-old Alyce Slim and her 9-year-old granddaughter Tiffany Lee. Slim and Lee were returning home after a visit to two women in Gallup. Slim drove Mitchell and Orsinger to their requested location, but when there both attacked her and Lee; The duo produced a knife and stabbed both multiple times, with Mitchell slitting Lee's throat, bludgeoning Slim with rocks and stabbing her to death. Afterwards, when both were dead, they dragged both their bodies into the nearby woods, decapitated their bodies and lit them on fire. Both then buried their remains in a shallow grave. They then carjacked their vehicle and kept it in their possession. On October 31, three days after the murders, three armed men robbed the Red Rock Trading Post Office while wearing Halloween masks, and used Slim's vehicle as a getaway car. They ended up abandoning the car on November 1 and attempted to light it on fire.
