The head of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives has been demoted in a shake-up over the controversial anti-gun trafficking program known as “Fast and Furious.” Kenneth Melson, acting director of the ATF, will become a senior adviser on forensic science at the Justice Department’s headquarters in Washington. In addition to Melson’s reassignment, Phoenix-based U.S. attorney Dennis Burke has stepped down from the Justice Department. Both men were closely involved in the gun sting that saw U.S. agents encouraging the sale of thousands of guns to middlemen for Mexican drug cartels in an attempt to gain access to senior-level figures within Mexico’s criminal organizations. The weapons were eventually linked to numerous crime scenes in the United States and Mexico, including the slaying of a U.S. Border Patrol agent.