(CBS News) A Boston auction house is showing 290 artifacts connected to the assassination of President John F. Kennedy. The items include the wedding ring owned by Lee Harvey Oswald, Kennedy's assassin, which has never been seen by the public.
While Oswald's simple gold ring almost slipped through the cracks, it is now providing clues as to what the gunman may have been thinking the day he killed JFK.
In 1961, after Oswald defected to the Soviet Union, he bought the ring for his Russian bride Marina Prusakova. He and his wife later moved to Dallas and separated.
The night before the assassination, Oswald came to stay with her in the nearby suburb of Irving. The next morning, he left the ring and $170 in cash on her nightstand. Hours later, he shot and killed the president.
The ring he left on his wife's nightstand was taken by the Secret Service in 1963 and then seemingly disappeared. It might never have been found were it not for the efforts of a Dallas-area investigator, Dave Perry.
Perry has spent four decades studying the Kennedy assassination. In 2004, a Dallas law firm asked him to take a look at a box of old documents.
"I keep going through the box and I find this little envelope," he said. "I open the envelope, and out fell a wedding ring. This was, to me, like finding pieces of eight off a Spanish galleon - if I could prove the provenance."
The proof was a tiny stamp found by a jeweler at the auction house, RR Auctions.
"In Lee Harvey Oswald's wedding ring, is a Soviet star with a hammer and sickle, a maker's mark from the Russian government telling us, this wedding ring was made in Russia," said Bobby Livingston from RR Auctions.
His widow wrote that in Russian tradition, taking off a wedding ring is considered a bad omen. She had never before seen her husband do it.
"I can only believe that the reason he did that is because he figured he was not coming home, one way or the other," she wrote.
Marina Oswald, now Marina Porter isn't granting interviews, but in a five page letter that will go to the buyer of the ring, she explained why the piece of jewelry is up for sale.
"At this time of my life, I don't wish to have Lee's ring in my possession because I want to let go of my past that is connecting with Nov. 22, 1963," she wrote.
Online bidding has already begun, and the ring is already up to $30,000. Another item, an actual window from the book depository building, is up to $150,000. The live auction takes place Thursday in Boston.