Sen. Chuck Grassley, investigating whether an undercover federal operation contributed to the slaying of a U.S. Border Patrol agent, said Thursday the ATF instructed an Arizona gun dealer to engage in "suspicious sales" despite the dealer's concerns that the weapons could "end up south of the border."In a letter this week to Attorney General Eric H. Holder Jr., the Iowa senator described as "untrue" personal assurances the Bureau of Alcohol, Tobacco, Firearms and Explosives gave to the gun dealer in an email saying "safeguards were in place" to prevent further distribution of the numerous weapons sold, including AK 47 assault rifles.

More...