The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives has locked up more than 1,000 people by enticing them to rob drug stash houses that did not exist, reports USA Today. The controversial ploy is a key part of the ATF’s crime-fighting arsenal. The stings are so aggressive and costly that some prosecutors won’t allow them. They skirt the boundaries of entrapment, and they have left at least seven suspects dead. ATF has quadrupled its use of such drug house operations since 2003, and officials say it intends to conduct even more as it seeks to lock up the “trigger pullers” who menace some of the most dangerous parts of inner-city America. USA Today concludes that “an ATF strategy meant to target armed and violent criminals has regularly used risky and expensive undercover stings to ensnare low-level crooks who jump at the bait of a criminal windfall.” The stings reflect a shift by federal law enforcement away from solving crimes in favor of investigating people the government thinks are criminals.