Few things say local like the Chesapeake blue crab.

It has scuttled its way into Maryland’s tourism slogan and is part of the region’s signature dish, proudly touted on menus and in markets as a taste of the Bay in an era when “eat local” has become the mantra of foodies.

But a few years ago, a tipster reached out to authorities with an unsavory allegation: A major Virginia seafood supplier was selling packages of premium Chesapeake blue crab meat cut with cheaper foreign crab. It wasn’t even the same species.

In an unusual probe, federal agents fanned out to markets across Virginia, Delaware and North Carolina, scooping up crab meat from Casey’s Seafood and sending it out for the type of DNA analysis more common in rape and murder cases.