TALLAHASSEE, Fla. -

Thirteen people from Florida and Georgia have been charged in what state investigators called a "criminal conspiracy" to sell artifacts stolen from state-owned lands in Florida.

Florida Fish and Wildlife Conservation Commission officers described a nearly $2 million black market in illegal historical artifacts. Items shown at a Wednesday news conference included dozens of pot shards and arrowheads.

Those arrested were called the "main dealers and looters." Some were accused of sneaking onto historical sites at night and digging in the dirt with hand tools.

Investigators said the recent arrests resulted from a two-year-long investigation that used an undercover operative posing as a buyer. The looted artifacts often were listed on websites such as Craigslist and turned up at trade shows.