Using DNA Database, Police Say They’ve Identified A Killer

Using DNA Database, Police Say They’ve Identified A Killer

Genetic tests links man, now dead, to 1994 Rockville murder

| Published:

Kenneth Earl Day, age 29

Photo courtesy Montgomery County police

A man who beat a Montgomery County research scientist to death in the early 1990s evaded authorities until nearly two years after his death, county police said.

Montgomery County police announced Friday they had identified the man responsible after years of investigation and by tapping into a DNA database of families.

Police said Kenneth Earl Day, a West Virginia man with ties to Montgomery County, murdered Le Thi Bich-Thuy and that he could be responsible for other undisclosed, unsolved local crimes.

On Oct. 5, 1994, police found the body of Thuy, a Children’s Hospital scientist, fatally strangled and beaten, outside her Rockville home. She had been raped, beaten and left for dead nearly a week earlier police said at the time, and they were unable to determine who had killed her or why.

A molecular biologist, 42-year-old Thuy had immigrated to the United States to work at the Rockville-based branch of the hospital in 1992, according to her obituary.

Five years earlier, a 52-year-old woman was walking on Lewis Avenue in Rockville when a man grabbed her from behind, physically assaulted and raped her.

Police recovered DNA evidence from both scenes and the crimes were determined to have been committed by the same person, but there was no match when the genetic material was cross-referenced with a national DNA database.

For more than two decades, the cases remained cold, with DNA information run through national databases coming back without matches.

Last summer, police re-ran the DNA through a different database that creates composite sketches – including eye, hair and skin colors, face shape and prevalence of freckles – of the people from whom the genetic material was taken.

Day’s sketch was released to the public with a $10,000 reward offered for anyone who could identify him, but nobody came forward, so police ran the DNA through a third database that identified people with a “significant amount” of shared DNA.

Ultimately, genetic material gathered during his autopsy confirmed Day’s connection to the rapes and murder.

Day died on March 24, 2017, in West Virginia at age 52. He moved from Montgomery County around 1997, according to police, and worked as a carpenter in various areas of Maryland and West Virginia.

Police across the country have used similar methodology to identify suspects in cold cases including the Golden State Killer, who was suspected of raping and murdering dozens of women in the 1970s.

But opponents say using genealogy data from national databases is unethical and could lead to discrimination. There is little data to support those claims, according to an article published Friday by Slate, an online magazine.

“Forensic use of genealogy data will certainly help investigators to solve some of their most puzzling crimes,” the article says. “But we have to resist the temptation to adopt these new, powerful tools without thinking through their consequences and ethical complexities.”


Caitlynn Peetz can be reached at

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