An original copy of the Bill of Rights, stolen from the North Carolina statehouse during the Civil War, was recovered in an undercover sting, the FBI said Wednesday.
Authorities learned of the document after a broker contacted the National Constitution Center, a museum being built in Philadelphia's historic district.
Museum president Joseph Torsella thought it might be the copy belonging to Pennsylvania, one of five states that have lost their copies over the years. But during the talks, his staff came to believe it was the copy stolen from North Carolina, based on handwritten information on the back.
Torsella, working with Pennsylvania Gov. Ed Rendell, a museum board member, then contacted authorities.
An FBI agent, posing as a philanthropist trying to buy the document for the museum, met Tuesday with a broker representing the seller, who wanted $4 million for it, authorities said.
After some discussion, the broker called a courier.
"A courier appeared with this document in a cardboard box, if you can believe that," said Jeffrey A. Lampinski, special agent in charge of the FBI's Philadelphia office.
The handwritten document -- one of at least 14 copies made in 1791 for the first 13 states and the federal government -- is faded but in "reasonable condition," Torsella said.
Curators estimated its value at $20 million to $30 million, he said.
Investigators would not release any information about the seller or broker, and officials said a civil seizure warrant was sealed. No arrests were made.
A federal judge in North Carolina signed the warrant, based on probable cause that stolen property had been transported across state lines, and that court ultimately will rule on whether the state is indeed the legal owner.
Officials believe the document was stolen by a Union soldier, who brought it back to his native Ohio and sold it a year later, in 1866.