An investigation into drug sting operations conducted by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) finds most people arrested are racial or ethnic minorities, according to USA Today.

ATF has more than quadrupled use of sting operations in the past 10 years, the article notes. The bureau entices suspects to rob a drug stash house that does not actually exist, in exchange for a promise of as much as $100,000. Prison sentences resulting from the sting operations can be a decade or more.

The newspaper reviewed court files and prison records, and found at least 91 percent of those arrested were racial or ethnic minorities–almost all of them black or Hispanic. That rate is much higher than among people who are arrested for violent crimes in big cities, or for other drug and gun offenses or other federal robbery.

Informants said in some cases, they identified targets for drug stings after meeting them on the street. “There’s something very wrong going on here,” said University of Chicago law professor Alison Siegler. “The government is creating these crimes and then choosing who it’s going to target.” Siegler is part of a team of lawyers challenging the ATF’s tactics in an Illinois federal court.

ATF officials disputed the charge that the operation is targeting minorities. They said they are focusing on people who already have long arrest records for violent crimes. “There is no profiling going on here,” Melvin King, ATF’s Deputy Assistant Director for Field Operations, told the newspaper. “We’re targeting the worst of the worst, and we’re looking for violent criminals that are using firearms in furtherance of other illegal activities.”