The murder of Stephanie Isaacson
Las Vegas, Clark County, Nevada · 1989
Overview
Stephanie Isaacson, a 14-year-old Las Vegas girl, was sexually assaulted and strangled on the morning of June 1, 1989, while walking a shortcut to Eldorado High School in eastern Clark County, Nevada. Her body was found the same day in a desert lot near her path. The case went unsolved for 32 years. In 2021, after a private donation funded the work, the Texas forensic lab Othram used Forensic-Grade Genome Sequencing to build a genealogical DNA profile from only about 120 picograms of preserved evidence, roughly the equivalent of 15 human cells, then the smallest amount of DNA ever used to identify a suspect. Investigative genetic genealogy led detectives to Darren Roy Marchand, who had died by suicide in 1995 and whose preserved DNA from a 1986 murder case confirmed the match.
How it was solved
By 2021 the Las Vegas Metropolitan Police Department had only a tiny, degraded sample of male DNA recovered from semen on Stephanie Isaacson's clothing, an amount earlier in-house testing in 1998 and 2007 could not turn into a usable profile. In January 2021, cold case detectives selected the case to test the limits of new technology, and the work was funded by a $5,000 donation from Justin Woo, a Henderson retiree and founder of the nonprofit Vegas Helps. The sample, about 120 picograms or 0.12 nanograms, fewer than 15 human cells, was sent to Othram Inc. in The Woodlands, Texas. Over roughly seven months, Othram scientists applied Forensic-Grade Genome Sequencing to build a single-source genealogical profile from the minuscule sample, and the company's in-house genealogy team used genealogical research to develop investigative leads that pointed to Darren Roy Marchand. Marchand had died by suicide in 1995 at age 29, so investigators turned to preserved biological evidence from his 1986 arrest in the strangulation of Nanette Vanderburg, a case that had been dismissed for lack of evidence. That reference DNA matched the profile from Stephanie's case, and the same comparison also tied Marchand to Vanderburg's killing. LVMPD announced the resolution on July 21, 2021, describing the 120-picogram sample as a world record for the smallest amount of DNA used to solve a case.
Sources
- Suspect in 1989 slaying ID'd using world's smallest sample of DNA evidence
“A Texas forensics lab had taken that tiny amount of genetic material, the equivalent of fewer than 15 human cells, and identified the teen's alleged killer.”
- How cold case detectives solved a 1989 murder case
“Police sent 0.12 nanograms of DNA, approximately 15 human cells, to the Othram lab in Texas, which built a genetic profile and constructed family tree connections.”
- Cold case of 14-year-old killed in 1989 solved with record-small DNA sample
“The minuscule DNA sample is the smallest amount ever used to solve a case, Las Vegas Metropolitan police officials said.”
- DNA testing reveals killer in 1989 strangling of Las Vegas schoolgirl
“Marchand was suspected in the 1986 strangulation death of Nanette Vanderburg, 24, but that case was dismissed due to lack of evidence.”
- DNA Proves He Raped, Killed a Girl, and Someone Else
“Marchand was charged with fatally strangling Vanderburg when he was 20; the case was dismissed, and he died by suicide in 1995 at age 29.”
- 32-Year-Old Las Vegas Cold Case Solved, Setting New DNA Testing Benchmark
“The 120 picograms of DNA is the smallest quantity ever used to successfully create a genealogical profile for a criminal investigation.”
- After 32 Years, Stephanie Isaacson's Killer is Identified
“Othram scientists used Forensic-Grade Genome Sequencing to build a genealogical profile from only 120 picograms of DNA.”
- 32-year Las Vegas cold case cracked with breakthrough DNA technology
“It is, for an announced case, the smallest amount of DNA reported that's been used to identify a suspect, said Othram CEO David Mittelman.”
- Police Say Donations Led to DNA Testing Which Solved Cold Case Rape, Murder of 14-Year-Old Girl
“Justin Woo, a local retiree, donated $5,000 to fund cold case DNA testing; Stephanie disappeared June 1, 1989, en route to school around 6 a.m.”