Thursday, New York narcotics investigators announced 21 arrests of small-time prescription drug dealers operating on Craigslist, in an attempt to “make an example” of the sellers. According to the AP, police spokespeople say Craigslist represents “a largely overlooked niche of a burgeoning black market for prescription drugs.”

Most of the arrests were of amateur dealers–ie., people who don’t sell drugs regularly–selling small amounts of pills from their own prescriptions, in public locations, including Penn Station, Washington Square Park, and Midtown’s MetLife building.

NYC narcotics agents began answering Craigslist ads last year, and have made 63 buys for $29,400 so far.

(Photo: Laura Gilmore/Flickr)