Ben Herr shovels loads of topsoil into a pile near the grave of an unknown person at Oak Hill Cemetery earlier this year. University of Colorado researchers are trying to find out who was buried there.

The century-old murder mystery that drew University of Colorado researchers to a gravesite in Lawrence’s Oak Hill cemetery may never be solved.

CU law professor Mimi Wesson said Monday that attempts to extract DNA from a scrap of shoulder bone retrieved from Oak Hill have thus far yielded no answers.

“I’m waiting for the lab biologists to tell me that there’s nothing more they can do,” she said. “They haven’t told me that yet.”

Wesson in May led an expedition to unearth the remains in hopes of solving the mystery that spurred a lengthy court battle in the late 1800s and led to the creation of an important piece of federal evidence law.

The key question: Does the grave hold John Hillmon or Frederick A. Walters?

In late 1879, Hillmon bought a $25,000 life insurance policy and set off from Lawrence on a trek to find ranch land. His companion, John Brown, later showed up at a rural home near Medicine Lodge and reported accidentally shooting Hillmon.

But at a time when insurance fraud was rampant, insurance companies suspected it was a scam. They believed Hillmon and Brown killed a third man, Walters, and buried him to collect on the policy.

The case went through the courts and was taken up by the U.S. Supreme Court twice. An appeal to the court created a new exception to the hearsay rule, permitting as evidence a letter from Walters’ fiancee stating his intentions to travel with Hillmon.

Wesson, who has taught students about the case for years, set out to solve the mystery. She called on CU anthropology professor Dennis Van Gerven to assist in the excavation. The researchers unearthed bits of bones and teeth.

DNA analysis was attempted using a small piece of clavicle bone. But water and microorganisms in the burial site have stymied efforts to identify the remains.

Wesson, who is writing a book about the case, said the lack of an answer to the riddle is discouraging to some, but not devastating.

“I love an unsolved mystery,” she said.