SIOUX FALLS, S.D. (AP) — A week after local, state and federal officials busted tobacco shops in Sioux Falls for synthetic drugs, U.S. Attorney Brendan Johnson has vowed to shut down the dealers.

Three Sioux Falls tobacco shops were among shops raided across the country last week as part of a nationwide sweep to seize cash, property and synthetic drugs.

Johnson spoke at a news conference Wednesday with several local law enforcement officials. He says officials are working hard to keep synthetic drugs off the streets.

Officials say that although the South Dakota Legislature passed laws banning synthetic drugs, people change the recipe to get around it. So officials say a federal law that bans analog drugs is helpful in prosecuting cases. Analog drugs have the same effect as illegal drugs.

(© Copyright 2012 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)