Items belonging to an Englishman credited with cracking encrypted Nazi communications during World War II and who later earned accolades as one of the founding fathers of computer science were discovered in the possession of a Colorado woman in 2018, nearly four decades after they went missing. 

In late August, Denver-based federal investigators flew across the Atlantic to return those items — which were enthusiastically received.  

"We thought probably that was the last we were ever going to see of them," said Dominic Luckett, headmaster at Sherborne School, in BBC coverage of the repatriation ceremony. "So it was a rather pleasant surprise when we got wind that the American authorities knew they were in America and they were doing their best to track them down and get them back."  

But that's not the end of the story: How those artifacts got to Colorado, and whether they were stolen or secretly given away — are mysteries that have not been solved.

The story took a dramatic turn in 2018 in Boulder when a woman from Conifer, Colo. presented the items to officials at the University of Colorado. She offered to lend the artifacts to the university for historical display.      

The university's historians thanked the woman for the offer but turned her down. Evidently, they knew what they were looking at, or at least had a solid idea about the items' significance. They contacted local authorities, who then contacted federal authorities. 

That's when Homeland Security Investigations Special Agent Greg Wertsch stepped into the case. 

"We did a search warrant on the property, we recovered the items, and then did subsequent investigations to authenticate the items that we had," Wertsch told CBS News Colorado.  

The box of items had been donated in 1965 to the Sherborne School in Dorset, England, located three and a half hours southwest of London. It was given to the all-boys school by the mother of Alan Turing, one of the school's most renowned students. 

• The enigma of WWII codebreaker Alan Turing

Turing attended the school from 1926 to 1931. He went on earn degrees at Cambridge and Princeton, author groundbreaking articles on computing, artificial intelligence and mathematical biology and became a national hero by developing a device to decode the German military's secret communications. 

The Nazis encrypted their messages with an Enigma machine. That ability to hide its communications was critical in building an advantage with its fleet of U-boats, a type of submarine. 

• Breaking the Nazi's Enigma codes at Bletchley Park

That is, until Turing decoded it and took away that advantage. HSI's Wertsch points out that it helped the Allies win World War II, saving millions of lives in the process. 

"At the time, we had no computer technology to decipher codes. Alan Turing worked on this problem," Wertsch said. "Alan Turing was principle in that, in determining how to break the code. That changed the course of the world war."

Turing died a controversial death in 1954. He was posthumously awarded an Order of the British Empire medal for his war effort. 

That medal, along with his Princeton Ph.D diploma, a personal note from the King George VI of England, a number of school reports and several school report cards were among the items in a box of artifacts that vanished from the Sherborne School in 1984. 

School officials don't know how the items disappeared. But they did determine that they vanished during a visit by a young woman from America. 

That woman told the school her name was Julie Schinghomes. She claimed to be doing a study on Turing. She received a tour of school's archives from a staff member. 

Somehow, when she left, the items went with her.

"We don't know precisely if they were stolen or given," Wertsch said. "There is a claim that some of the items may have been given by one person at the school to someone here. However, that person would not have the authority to give them."

According to federal prosecutors, Schinghomes returned home to the United States and changed her name to Julia Turing. Investigators have not found her to be related to Alan Turing in any way.

The search warrant was issued in 2021. Investigators found the artifacts and took possession of them. 

But it would be another year and a half before a settlement was reached between Julia Turing and federal investigators.

Wertsch said Julia Turing surrendered her interest in the items — after lengthy and "laborious discussions" — in exchange for prosecutors dropping their criminal case against her. 

"Everybody in this case came together and agreed, the place for these items was back where they first were," Wertsch said.

However, Chris Larson, a spokesperson with the United States Attorney Office in the District of Colorado, declined to comment when asked if, in fact, Julia Turing faced no legal consequences stemming from her actions. 

Regardless, the items are back where they belong, Wertsch said. "I'm very lucky to have had a small part in preserving that legacy for the world," he said.

Messages left with a relative of Julia Turing requesting comment were not initially returned.