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32-year Las Vegas cold case cracked with breakthrough DNA technology

The case of 14-year-old Stephanie Isaacson proves to be a breakthrough case for DNA evidence. (KSNV)
The case of 14-year-old Stephanie Isaacson proves to be a breakthrough case for DNA evidence. (KSNV)
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On the morning of June 1, 1989, 14-year-old Stephanie Isaacson left for class at El Dorado High School.

She never made it.

Police say her parents called officers, who began an extensive air and land search for Stephanie.

That evening, near the intersection of Stewart Avenue and Nellis Boulevard, her books and belongings were discovered. Nearby, officers also found her body.

Police say Stephanie had significant blunt force trauma injuries; she was strangled and sexually assaulted.

Officers attempted to find leads to no avail. DNA from the case was uploaded to the national database, called CODIS, but there were no matches.

Then in 2021, the break they needed.

"This was a huge milestone," said David Mittelman, CEO of forensic laboratory company Othram in Texas.

His company has helped solve hundreds of cold cases with their specialized technology.

Their success caught the eye of Justin Woo, founder of nonprofit Vegas Helps.

“I’m very interested in technology, that’s my background," he said in a phone interview to News 3 while vacationing in Greece. "And Othram has been doing this amazing work trying to solve cold cases.”

Woo offered to fund testing for any LVMPD cold case.

At Wednesday's press conference, authorities explained Stephanie's case was chosen specifically because of the minimal amount of DNA available.

And minimal is putting it mildly.

"The equivalent of 15 cells was submitted for this testing," said Kimberly Murga, director of laboratory services with LVMPD.

For reference, Mittelman explained getting a DNA swab for companies like 23andMe gather around 750 to 1,000 nanograms of DNA. This case was .12.

"It was very scary to take on this project because I believed we consumed the remainder of the evidence in this case," said Mittelman. "It is, for an announced case, the smallest amount of DNA reported that’s been used to identify a suspect in a crime."

But Othram's specialized technology helped crack the case.

"We have very sensitive methods that can access evidence that is very old," he said. "We are using brand new technology that didn’t even exist a few years ago.”

Mittelman said the lab used "genome sequencing," the same method used to catch the Golden State Killer back in 2018.

Finding a suspect through building a family tree out of public databases, where people have given consent to use their data.

"If I match against someone with a known identity, I can know what their family tree looks like," said Mittelman. "Then I can piece together enough of a family tree to see what’s missing, where would this unidentified person fit in.”

Through a distant cousin, Mittelman said they were able to finally make a match: Las Vegas resident Darren Roy Marchand.

Police believe he killed Stephanie randomly. Marchand had been previously arrested in connection to the murder of Nanette Vanderburg in 1986, but the case was dismissed. Investigators compared Marchand’s DNA from the case involving Nanette to Stephanie’s case, resulting in a match.

Marchant died by suicide back in 1995.

At Wednesday's press conference, LVMPD Lt. Ray Spencer read a statement from Stephanie's mother.

“I’m glad they found who murdered my daughter. I never believed the case would be solved," he read. “We will never have complete closure because nothing will ever bring our daughter back to us.”

Mittelman hopes the record-low DNA quantity from this case shows other law enforcement agencies across the country that solving decades-long cold cases is possible.

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