Not a day goes by that Jeff Neilson doesn't think about the decades-old killing of his 21-year-old wife, Tracey
Credit: Oklahoma State Bureau of Investigation

Not a day goes by that Jeff Neilson doesn’t think about the decades-old killing of his 21-year-old wife, Tracey — and the moment he found her lifeless body in their home, riddled with stab wounds.

Jeff had returned to the couple’s home in Moore, Oklahoma, on the night of Jan. 5, 1981, after a day of classes at the University of Oklahoma. He found Tracey splayed out on their bloodied bed.

“It was a horrible day,” Jeff tells PEOPLE in this week’s issue, on newsstands now, as the 37th anniversary of his wife’s killing approaches.

“During my first years at medical school, I was dissecting cadavers, but nothing prepares you for that … it was absolutely horrible.”

Investigators in Oklahoma are making a new push to solve Tracey’s killing, reaching out to the public with hopes of generating tips that may lead, at last, to the killer’s apprehension and arrest. While there have been precious few developments in the cold case in 30-plus years, detectives — and Tracey’s widower — haven’t abandoned all hope.

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“I’m not entirely sure what closure means, but I do think knowing what happened would help, in some ways, in dealing with the psychological repercussions of what happened to Tracey,” says Jeff, a 56-year-old orthopedic surgeon in Paris, Texas.

After finding his wife dead that night in 1981, Jeff says he “went crazy for a minute” before heading toward the front door. He exited the home, ran down the street to a friend’s house and called 911.

“Tracey was just a joy to be around,” Jeff tells PEOPLE. “Everyone loved being around her. She was beautiful and fun and just wonderful to be around. She was extremely smart and funny and I loved being around her … she is missed by essentially everyone who knew her.”

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For decades after the killing, his wife’s death plagued his daily thoughts, sometimes overwhelming him. But “time dampens the severity of your pain,” Jeff says.

“It is still something you think about on a daily basis and it continues to hurt,” he says.

While frustrated by the lack of answers to Tracey’s cold case, Jeff tells PEOPLE his wife’s keychain — which investigators believe the killer may have taken as a “souvenir” — is still missing and could be the key to solving this crime.

“That key ring would be one way to link someone” to the killing, he explains. “We hope a mistake is made. I think we’re doing a Hail Mary pass here and trying to do whatever we can to stimulate one phone call to authorities that could lead to something.”

Anyone with information about the case is urged to call the Oklahoma State Bureau of Investigation at 800-522-8017.

• Reporting by JOHNNY DODD