DNA scientist James Watson's Nobel Prize was returned to him earlier this week.
Alisher Usmanov, the richest man in Russia, bought the medal for a record $4.7m at Christie's New York on December 4.
Watson was a member of the team that discovered the structure of the DNA molecule in 1953, but was forced to sell it after falling on hard times, although a proportion of the proceeds went to charity.
He was shunned by the scientific community for a series of offensive statements on race during the mid 2000s.
Usmanov explained his decision: "In my opinion, a situation in which an outstanding scientist has to sell a medal recognising his achievements is unacceptable.
"Dr Watson's work contributed to cancer research, the illness from which my father died. It is important for me that the money that I spent on this medal will go to supporting scientific research, and the medal will stay with the person who deserved it.
"James Watson is one of the greatest biologists in the history of mankind and his award for the discovery of DNA structure must belong to him."
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