The Record

The investigations you've read about.

Every case below was led or supported by an IRIS team member during their law-enforcement career. It's the same experience we bring to private engagements.

Solved after three decades 1991 – 2023

Sarah Yarborough

Head detective, King County Sheriff's Office

Sarah Yarborough was 16 when she was murdered on the Federal Way High School campus in 1991. Male DNA from the scene was submitted to state and national databases for years without a match. Kathy Decker led the investigation through repeated re-evaluation of that evidence as technology advanced, and through the forensic genetic genealogy work — beginning with Dr. Colleen Fitzpatrick in 2011 — that eventually narrowed the profile to two brothers. Patrick Nicholas was identified in 2019, and DNA from a discarded cigarette matched the crime-scene profile. He was convicted and sentenced in 2023.

Featured on Bloodline Detectives

ABC News — arrest announced Kent Reporter — charges filed Federal Way Mirror — trial

Conviction, 2013 2006 – 2013

Nicole “Nikki” Pietz

Investigation and forensic tracking examination

Nicole Pietz, a 32-year-old from Seattle, disappeared in January 2006; her body was found in a wooded area near Burien. Kathy Decker partnered with lead detective Jesse Anderson on the investigation and provided a forensic visual tracking examination. Nicole's husband, Martin David Pietz, was convicted of second-degree murder in 2013 and sentenced to 220 months.

Featured on Dateline NBC — “Secrets in Seattle,” aired November 20, 2013

ABC News — conviction

Remains recovered 2003

The Knotek Case

Oversaw the evidence search, King County Major Crimes

At the request of the Pacific County Sheriff, King County's Major Crimes Unit was asked to assist in the Knotek torture-and-homicide investigation in Raymond, Washington. Kathy Decker spent several weeks on the property overseeing the extensive search for human remains. Remains were recovered, along with the forensic and DNA evidence that linked them.

Subject of the documentary series Wicked Attraction

The Seattle Times — pleas entered

48 counts of aggravated murder 1982 – ongoing

Green River / Gary Ridgway

Evidence search command, King County Sheriff's Office

The Green River investigation is described by King County as one of the longest and largest serial murder investigations in U.S. history. Gary Ridgway was arrested in 2001 and pleaded guilty in 2003 to 48 counts of aggravated murder in the first degree. Kathy Decker oversaw the evidence search at Ridgway's residence and coordinated evidence searches for victims' remains over the years that followed.

CNN — sentencing King County Sheriff's Office — case record

Details above are drawn from public reporting and from the investigators' own accounts. Current and ongoing work is confidential; a number of engagements are covered by non-disclosure agreements and are not described here.

Expert Commentary

When the national press needs DNA explained, they call our expert.

Suzanna Ryan is IRIS's forensic DNA and genetic genealogy expert — 27 years in forensic serology and DNA analysis, and an expert witness accepted over 150 times. Outside her casework she is one of the most sought-after DNA commentators in true crime, asked to explain what the evidence in a case can and cannot prove.

Suzanna Ryan

Forensic DNA & Genetic Genealogy Expert

Full background

The Zodiac Killer

Featured DNA expert on the History Channel's Hunt for the Zodiac Killer and on a Netflix documentary — including the M-Vac evidence recovery attempted on the Cheri Jo Bates homicide.

Wrong Man — Starz

Retained by the producers to review the crime-scene DNA evidence and testing recommendations in the Kenneth Clair case.

The Nancy Guthrie case

National commentary across Fox News, NewsNation, and major true-crime podcasts.

Forensic Files

Featured expert on Forensic Files and Forensic Files II.

National networks

Guest DNA expert on CNN (the Rebecca Zahau case), Oxygen (the West Memphis Three), CBS News, ABC News, Court TV, HLN, and Discovery Channel.

Podcasts

Nancy Grace, The Megyn Kelly Show, Laura Ingle, Anne Emerson, and a range of other true-crime shows.

Appearances above are as an independent forensic DNA expert commenting on the case or subject named. Except where a retained review is stated, they do not indicate involvement in the underlying investigation.

Media

Where our team's work has been covered.

Pietz investigation
Yarborough cold case
Knotek case
Team casework and production
Forensic DNA and geographic profiling commentary
Forensic DNA and geographic profiling commentary
Geographic profiling commentary
Investigative commentary

Press & Media

Working on a story?

For interview requests or background on any of the cases above, reach us directly — we're used to working to a deadline.

(208) 999-8460

Confidential Case Review

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