The U.S. on Wednesday returned a letter from Christopher Columbus, detailing his travels to the Americas, after it was discovered the document was stolen from Spain.
Immigration and Customs Enforcement (ICE) announced the letter would be returned after a seven-year investigation into the document, which is known as the Catalonia Plannck II Columbus Letter.
"I am pleased to be able to return a priceless piece of cultural property to its rightful owners," Homeland Security Investigations acting Deputy Executive Associate Director Alysa Erichs said in a statement obtained by CNN.
The letter from Columbus addresses King Ferdinand and Queen Isabella and details his 15th century travels.
The probe was launched in 2011 after ICE and the Department of Justice were notified that various manually printed copies of the letter were stolen from libraries in Europe.
Investigators discovered in 2012 that one of the 80 copies of the letter had been unlawfully taken from the National Library of Catalonia in Barcelona, and that the one in the library was a forged a copy, according to CNN.
The agency said the letter was sold for $1 million in June of 2011, and that the most recent owner handed it over after "extensive negotiations with the US Attorney's Office for the District of Delaware," according to the network.