Finding out who killed 20-year-old Mary Petry and her 22-year-old boyfriend William Sproat at a home near Ohio State University's campus in 1970 would only bring small satisfaction to Mary's twin sister, Martha.
"I really would like to know why," Martha Petry said. "That's much more important than any punishment."
Martha Petry said she still has letters that her twin wrote her, every line crammed with information about Sproat, from what restaurant they had eaten at to how the pair enjoyed speaking in French to each other.
Petry said she and Sproat's sister both believe the person who killed their siblings may have known them because of how violent the crime was. The attempt to use new technology to try and find answers about what happened is a blessing for Petry.
"This is not about justice, it's more about mercy," she said. "The mercy is knowing the mystery. It has always been there, but it wasn't something that I could dig into because it had such an emotional weight to it, but during COVID, after I had retired, there was a new sense of asking why."
Should the evidence at the scene yield a potential genealogical match, Petry said she knows it may not give her the answers she's looking for about why her sister had to die.
"My universe is not one that's about an eye for an eye," Petry said. "There may be a reason. There may be understanding of something that I don't understand."
Columbus police have identified several dozen unsolved homicides that may be able to be solved with the use of genetic genealogy, an emerging technology.
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