Stephanie Isaacson

A high school girl is sexually assaulted and murdered in 1989. In 2021, her assailant was identified using the least amount DNA ever used in forensic genetic genealogy.

In June 1989, 14-year-old Stephanie Isaacson headed out on her morning walk to Eldorado High School. The Las Vegas teenager frequently took a shortcut through a vacant sandlot off Steward Avenue and Linn Lane to get to school quicker. After school let out that afternoon, Stephanie’s father began to worry when she did not arrive home at her usual time. Upon calling the school in hopes of finding out where she may be, it was revealed that Stephanie never made it to school. A missing person report was filed and law enforcement investigators then conducted a local search, canvassing the area around the typical route that Stephanie would take to school. Eventually, her body was found at a sandlot and investigators determined she had been sexually assaulted and strangled to death. Over the years, a lengthy investigation, spanning decades, ensued and all available investigative leads were exhausted. Stephanie's killer remained undiscovered.

Stephanie Isaacson was a young high school student in Las Vegas, on her way to school, when she was attacked and murdered by an unknown assailant.

It is all too common for cases involving sexual violence to remain unsolved, even after traditional forensic DNA testing is utilized. In spite of heroic efforts to “end” the backlog of hundreds of thousands of sex assault kits, about 85% of sex assault kits tested through CODIS will NOT produce an identity for the suspect. You can learn more about the effort to end the backlog by listening to this interview that I conducted with Ilse Knecht , the Director of Policy & Advocacy at the Joyful Heart Foundation. In just the time that I have maintained this newsletter, I have mentioned three examples so far: the cases of Siobhan McGuinness , Carla Walker , and Christine Jessop — all unsolved after traditional forensic DNA testing failed to produce leads. Decades later, all three cases were solved, in part, using Othram technology. Unfortunately, there are countless more cases that need advanced testing, in order to reach a successful outcome. We need to make sure this technology is available to all cases.

Back to Stephanie Isaacson, the Las Vegas Metropolitan Police Department teamed up with my company, Othram, in January 2021, to reexamine DNA evidence from the crime scene in hopes that advanced DNA testing might generate new leads in the investigation. Not all agencies have funding support for these newer DNA methods yet. We turned to the DNASolves® platform , which we use to crowdfund or seek private donor support for casework that otherwise cannot be funded. We had a relationship with a private donor local to the area and he offered to fully fund the required casework. The private donor is Justin Woo, founder of the non-profit organization Vegas Helps , and I highly recommend you all look him up.

Once we got started, Othram scientists used Forensic-Grade Genome Sequencing® to build a genealogical profile from the remaining DNA evidence — only 120 picograms (or 0.12 nanograms) of DNA. This case has set a new lower limit on the quantity of DNA required to build a genealogical profile for a suspect of a crime. The Othram genealogy team used the profile to develop investigative leads that were returned to LVMPD. The research step was a little tricky as the genealogical profile revealed a mix of French Canadian descent from New England and more recent French Canadian descent from Canada. However, about seven months after we received the DNA evidence to our laboratory, Othram returned leads to LVMPD and the detectives were able to confirm the identity of the suspect in Stephanie's sexual assault and murder. He was Darren Roy Marchand and he had died in 1995 by suicide. Remarkably, Marchand had been tied to a previous sexual assault and murder of a woman in 1986.

Three years before the death of Stephanie Isaacson, 25-year-old Nanette Vanderburg, was murdered. Marchand is the prime suspect in both crimes.

How did Othram work with such a small quantity of DNA evidence (the equivalent of about 15 human cells)? I have written before about how Othram accesses genetic information from evidence that has failed other methods — evidence that has been deemed “unsuitable for analysis”. Our methods outperform others, especially for cases with very little DNA. Prior to this case, we also helped identify Rodney Johnson from only slightly more DNA than was available in the Stephanie Isaacson case.

Let me present a comparison: In a typical consumer DNA test, the collection kit will collect 750 to 1000 nanogram of DNA. The suspect in Stephanie Isaacson’s murder was identified using only 0.12 nanograms — a quantity that other labs and lab methods are not set up to handle. I am personally grateful to Forensic Lab Director Kim Murga, Forensic Lab Manager Kellie Gauthier, and Cold Case Detective Terri Miller, for trusting Othram and giving us a chance to help with the case.

As a further point of comparison, I will add that in medical and consumer testing, labs can generally assume they will work with high quantity, high quality, single source DNA. In forensics, its hard to make any assumptions about the DNA. Most of the time, crime scenes have small quantities of DNA, the DNA is heavily degraded and is contaminated with non-human sources. Sometimes there are mixtures of DNA from multiple persons — such as in a sex assault (like this one) where there could be DNA from the perpetrator and the victim. Not surprisingly, the process for testing and analyzing forensic DNA evidence is very different than what you would need for medical or consumer applications.

The identified suspect in Stephanie Isaacson’s sexual assault and murder is shown in a photo from 1986. He committed suicide in 1995.

There are two important points that I want to leave you with. First, although forensic genetic genealogy is a very valuable technique for cracking unsolved cases, sending DNA evidence to the wrong laboratory, or testing the DNA with the wrong methods, will results in destruction of evidence and if there is no DNA left, a case can truly go “cold” forever. You can’t simply send DNA evidence anywhere and you should be definitely wary of folks that offer service but “outsource” elsewhere. Othram, for example, does not outsource any step of the testing process.

Second, it takes public support to make this work possible. Right now, anyone can help us solve the next cold case — either by financially supporting a case or submitting their own DNA data, in case they might be a distant relative to an unknown person. Many of these cases can be solved by combining crowdfunding, volunteered data, cutting-edge genomics, and tremendous teamwork. Its a lot of work, but its always worth the effort. You can learn more about how to get involved here . In the long term, however, we need to raise awareness for the technology and we need to push for this technology to be better supported by federal funds. There are a lot of cases to work — remember that “ending” the backlog is not the same thing as “solving” the backlog — and individual private donors can’t fund all the cases on their own!

If you want to learn more about the case of Stephanie Isaacson, here are some great links:

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