Marina Oswald Porter selling wedding ring of JFK assassin Lee Harvey Oswald

(UPI) -- Marina Oswald Porter, the widow of JFK assassin Lee Harvey Oswald, has given his wedding ring to an auction house and it went up for sale on Thursday.

Bobby Livingston, an executive vice president with RR Auction, described the ring as a "very powerful, significant piece of evidence. It gives you such insight into the mind of Lee Harvey Oswald." He believes that the ring could fetch $100,000 or more. “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.”

Porter only recently recovered the ring after a Dallas-area investigator, Dave Perry, found it in 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 50th anniversary of Kennedy's assassination in Dallas is in November and the ring is just one of almost 300 items that will be auctioned off.

Accompanying the ring is a five-page handwritten letter from May 2013 written by Porter. "At this time of my life I don't wish to have Lee's ring in my possession because symbolically I want to let go of my past that is connecting with Nov. 22, 1963," she wrote in the document.

Porter theorizes that Oswald knew what he was doing by leaving the ring behind.

"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.