The British scientist Alan Turing’s Princeton doctoral degree, OBE medal and other items of memorabilia have been recovered in Colorado, 35 years after they were taken from Sherborne School in Dorset.

Turing, a great of British science, was persecuted for his homosexuality and died in 1954, aged 41, his death ruled a suicide. His reputation has since been fully restored and celebrated.

In July 2019 a member of the government committee which decided he should appear on the new £50 note, Dr Emily Grossman, wrote in the Guardian: “His contribution to science is clear.

“[He was] the father of computer science, a significant influence on the modern field of artificial intelligence and most importantly, his work at Bletchley Park during the second world war led a team of code-breakers to crack the German Enigma code.”

In 2008, the Princeton Alumni Weekly named Turing the college’s second-most influential graduate, behind only James Madison, the fourth American president who was one of the authors of the US constitution. Six years later, in The Imitation Game, a film directed by Morten Tyldum, Turing was played by Benedict Cumberbatch.

On Friday, in court filings reported by the Boulder Daily Camera and other outlets, federal officials said they had recovered and were seeking the forfeiture of Turing’s degree certificate, the medal and photos, reports and letters from his time at boarding school.

The items were stolen in 1984, the filing said, after a woman asked to see the Turing archive at Sherborne. A note was later found which said: “Please forgive me for taking these materials into my possession. They will be well taken care of while under the care of my hands and shall one day all be returned to this spot.”

In 2018 a woman named Julia Turing offered the items on loan to the University of Colorado Boulder. The court filing said the woman was not related to the British scientist but changed her surname from Schwinghamer in 1988.

In a letter cited in the filing and reported by the Planet Princeton website, a Sherborne employee wrote: “I am familiar with the eccentricities of Americans but I got the impression that she has a ‘crush’ on Turing.

“One of my staff took her over to the librarian who gave her access to Turing’s bits n pieces. I did not see her again but she wrote expressing her joy at having a collection of Turing items and included a photo of them laid out on a table – his photo, OBE & so on. I was not aware that she had taken them, nor indeed was the librarian! I asked him to make a list of the missing items but it proved to be incomplete because we had no inventory anyway.

“I gave up any hope of ever getting AT’s things back ’til one day she wrote saying she was sending them back. A parcel arrived. It contained more than the librarian had listed, which made me cross. I wrote thanking her and she told me she intended to join the US Army and was training hard for the US Olympic team (track). I wished her luck and heard no more.”

That package evidently did not contain the certificate, medal and other items. In 2018, prompted by their being offered to the Colorado university library, federal officials searched a home and recovered the items. Should they ever reach the market, they could prove valuable: in 2015 one of Turing’s notebooks sold for more than $1m at auction in New York.

In her piece for the Guardian last year, Grossman wrote: “Turing’s importance goes beyond science.

“Shortly after the war, he was prosecuted by the British government for ‘gross indecency’ due to his relationship with another man. He chose to undergo a year of chemical castration rather than face a prison sentence, but he died two years later, aged 41. The inquest found that his death from cyanide poisoning had been suicide.

“In 2009 Gordon Brown issued Turing an apology on behalf of the government – and in 2013 the Queen officially pardoned him.

“This may have seemed too little, too late, but such public acknowledgment of his mistreatment by the state helped pave the way for the subsequent government pardoning of nearly 50,000 homosexual men who had been historically cautioned or convicted for homosexual acts.”