A 15th-century Christopher Columbus letter is finally back in Italy, decades after it disappeared from a Venice library and years after it resurfaced in Delaware.

U.S. Immigration and Customs Enforcement (ICE) announced that it repatriated the letter to Rome on Wednesday following a "multifaceted international investigation."

"This is the fourth original edition of this letter stolen over the past decades and we could not be happier to return it," Deputy Director Patrick Lechleitner said in a statement.

Columbus wrote it in 1493 to his patrons, Spain's King Ferdinand and Queen Isabella, describing his findings in the Americas. The letter was sent to Rome and reprinted in Latin as a pamphlet that ended up in libraries across Europe.

This particular letter is the most rare of all the copies that have been discovered in recent years, because it's a printing of the first edition. ICE placed its value at more than $1.3 million when it announced its discovery in 2020.

"Culturally significant artifacts are assigned a monetary value in the world's marketplaces in which they are traded," William Walker, acting agent in charge of Homeland Security Investigations (HSI) Philadelphia, said at the time. "But the cultural and symbolic worth of these objects far surpasses any given dollar value to the nations to whom they rightfully belong."

U.S. met with Italian officials met in Rome this week to return the letter, which is in the form of a slender hardcover booklet.

In a series of tweets, Italian Culture Minister Gennaro Sangiuliano thanked those involved in the effort, which also includes the U.S. Embassy in Italy and the cultural heritage protection branch of Italy's Carabinieri police.

Sangiuliano, describing Columbus as a fundamental figure in Italy's history, said the document will be enhanced with a traveling exhibition that will contextualize and help others appreciate it.

What the letter says

To understand the letter's importance, it's worth remembering what Columbus did. The explorer is famous for discovering the New World in 1492 — and launching centuries of European colonization and exploitation of the American continents and their indigenous inhabitants.

Columbus set sail from Spain in August 1492, looking for an all-water route to Asia. He made it to the Caribbean, where he spent several months exploring various islands including Juana (modern-day Cuba), Hispaniola (which is now split into Haiti and the Dominican Republic). He also left dozens of men behind to build a settlement in present-day Haiti.

Columbus kidnapped as many as 25 Native Americans to take back with him to Spain — only eight survived, according to the Gilder Lehrman Institute of American History. He also brought gold and certain native birds and plants.

Upon his arrival in Spain, Columbus wrote a letter in Spanish to King Ferdinand and Queen Isabella, who had helped fund his voyage, informing them of what — and whom — he had found in the Americas.

"I discovered many islands inhabited by numerous people," he wrote, according to an English translation. "I took possession of all of them for our most fortunate King by making public proclamation and unfurling his standard, no one making any resistance."

Columbus described the beauty and natural abundance of the islands he visited, taking care to note they are "easy to be traversed" and "most fertile both for cultivation and for pasturage."

He also collected his observations on the local people, describing them as "destitute of arms, which are entirely unknown to them, and for which they are not adapted ... because they are timid and full of terror."

"But when they see that they are safe, and all fear is banished, they are very guileless and honest, and very liberal of all they have," he added. "No one refuses the asker anything that he possesses; on the contrary they themselves invite us to ask for it. They manifest the greatest affection towards all of us, exchanging valuable things for trifles, content with the very least thing or nothing at all."

Columbus wrote that he had gifted them "many beautiful and pleasing things" he had brought with him to try to win them over, in the hopes they might become Christians, grow loyal to Spain and "be eager to search for and gather and give to us what they abound in and we greatly need."

He concludes by thanking Jesus and the Lord for this great victory and calling for celebration "not only for the exaltation of our faith, but also for the increase of temporal prosperity, in which not only Spain but all Christendom is about to share."

What happened to the letter

Columbus' letter was sent to Rome, where a prominent printer named Stephan Plannck reprinted it in Latin and distributed it across the continent.

Plannck accidentally left Queen Isabella's name out of the pamphlet's introduction, but quickly realized his mistake and reprinted the pamphlet a few days later. That's why there are two different editions, known as Plannck I and Plannck II.

The letter in question is a Plannck I, which ICE says makes it "exceptionally rare."

The Biblioteca Nazionale Marciana ("Marciana National Library") in Venice acquired the letter sometime in or around 1875, according to ICE. It says the document was stolen "at an unknown time between 1985 and 1988," without going into detail.

"Unlike prior recovered Columbus letters, this Columbus Letter-Plannck I was not replaced with a forgery, but instead was missing from the Biblioteca Nazionale Marciana for decades," ICE added.

Investigators determined that in May 2003, a collector "acting in good faith" unknowingly purchased that same letter from a rare book dealer in the U.S. It would take another 20 years for it to make its way back to Italy.

How investigators cracked the case

HSI Wilmington received information in 2011 regarding alleged forgeries of several Latin editions of the Columbus letter, according to ICE.

That led HSI to locate, seize and repatriate three such letters (all Plannck II) that had been stolen from European libraries. They returned one to Florence in 2016, and the others to Barcelona and Vatican City in 2018.

In June 2018, HSI Wilmington and HSI Rome asked the rare book expert they had been working with — Paul Needham, a former librarian at Princeton University — to compile a full list of all known Columbus letters in Italy. That's how they learned that a Plannck I letter had been missing from the Venice library since the 1980s.

"Based on the findings of the rare book expert and additional analysis conducted by staff from the Smithsonian Institution's Museum Conservation Institute, it was determined that the Plannck I Columbus letter stolen from the Marciana National Library was likely the same Columbus letter in the collection of a privately owned library located in the United States," ICE said.

HSI worked with the U.S. Attorney's Office for the District of Delaware to contact the collector and recover the letter. The collector cooperated with the investigation, authorities added.

Mark Olexa, an HSI special agent who has led the Columbus letter investigation letter for the past decade, said in a Twitter video that "we are really excited to be returning it to its rightful place with the government in Italy."

HSI investigations have facilitated the repatriation of more than 20,000 objects — including Nazi-looted art, Roman coins, Egyptian sarcophagi, Mongolian and Chinese dinosaur fossils and human remains — to over 40 countries and institutions since 2007, according to ICE.

In fiscal 2022, it adds, the program returned cultural property to more than 15 countries, including France, India, Iraq, Italy and Mali.