The pair was later arrested in Las Vegas and a polygraph test cleared them of the Walker murders. But in 1987, a polygraph expert said those tests in the early 1960s were worthless.
Authorities said the Walkers still have some living relatives both in and outside of Florida but declined to give names. McGath has been the one leading the effort to find their killers.
She hopes the DNA will prove that Smith and Hickock killed the Walker family so the community can have closure, and so the dozens of people falsely accused over the years as suspects in the case can finally have peace of mind.
Kirby said it's likely that only bones remain in the Kansas coffins.
"In this case, it's going to require a backhoe," he said. "Especially with the drought we had this year, the ground is going to be extremely hard."
Kirby hopes that if an exhumation occurs, officials will be able to get the material they need by simply opening the coffin on site, without full removal. He was also concerned about the timing of any exhumation, because relatives visit other graves and decorate them around Christmas.
Associated Press writer John Hanna contributed to this report from Lansing, Kan.
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