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How discarded chewing gum helped convict a serial rapist of two cold case murders

Krdo · · 1825 words · By CNN Newssource
Victim and Survivor Testimony Law Enforcement Strategy Forensic Science and Justice
open_in_new Read the original article: https://krdo.com/news/2026/05/14/how-discarded-chewing-gum-helped-convict-a-seri…

psychologyDetected Techniques

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Loaded Language 90% confidence
Using words with strong emotional connotations to influence an audience.
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Name Calling / Labeling 85% confidence
Attaching a negative label to a person or group to reject them without evidence.

fact_checkFact-Check Results

12 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

check_circle Corroborated 6
info Single Source 2
schedule Pending 2
verified Verified 1
help Insufficient Evidence 1
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“Mitchell Gaff opened the door wearing pajama pants, welcomed the trio into his house and agreed to a taste test, sampling different sticks of gum”
CORROBORATED
The specific detail about pajama pants and the gum taste test is reported by KRDO and corroborated by CNN and other web results describing the 'gum ruse' undercover operation.
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web search NEUTRAL — Mitchell Gaff is pictured in 2017 after registering as a sex offender in 2018 in Tacoma, Washington. A taste of freedom wrecked by a taste of gum. In 2024, Mitchell Gaff was 66 years old, living on hi…
https://www.aol.com/articles/chewing-gum-leads-sexual-sadist…
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web search NEUTRAL — Gaff had unknowingly given three undercover detectives the DNA they needed to confirm his connection to a 1984 rape and murder, according to an affidavit of probable cause filed in March. The “gum rus…
https://www.cnn.com/2026/05/10/us/mitchell-gaff-everett-wa-c…
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web search NEUTRAL — Mitchell Gaff, seen in this file image, pleaded guilty to two counts of first-degree murder earlier this year. (Photo: KOMO News).Investigators said a DNA sample obtained from a piece of gum Gaff chew…
https://komonews.com/news/local/two-1980s-cold-case-murders-…
+ 1 more evidence source
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“Gaff had unknowingly given three undercover detectives the DNA they needed to confirm his connection to a 1984 rape and murder”
CORROBORATED
Multiple sources, including CNN and other news reports, confirm that DNA from chewing gum was used to connect Mitchell Gaff to a 1984 rape and murder.
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web search NEUTRAL — DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essen…
https://en.wikipedia.org/wiki/DNA
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web search NEUTRAL — Jul 9, 2025 · DNA (deoxyribonucleic acid) is a set of instructions for creating the proteins that make your body work. Two strands of DNA together form a double helix — a bit like a spiral staircase.
https://my.clevelandclinic.org/health/body/dna
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web search NEUTRAL — 1 day ago · DNA is an organic chemical of complex molecular structure found in all prokaryotic and eukaryotic cells. It codes genetic information for the transmission of inherited traits.
https://www.britannica.com/science/DNA
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“Gaff, 68, a convicted rapist, admitted April 16 to the killing of Judy Weaver and also of Susan Vesey four years earlier”
CORROBORATED
KRDO and other news sources confirm that Gaff, 68, admitted on April 16 to the killings of Judy Weaver and Susan Vesey.
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web search NEUTRAL — Mitchell Gaff, 68, a convicted rapist, admitted April 16 to the killing of Judy Weaver and also of Susan Vesey four years earlier, according to court documents. https://cnn.it/4tpqo72. No alternative …
https://www.linkedin.com/posts/cnn_mitchell-gaff-68-a-convic…
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web search NEUTRAL — Mitchell Gaff, a convicted serial rapist, now stands charged with two gruesome murders after DNA collected from his gum matched old crime scenes.Gaff was charged on March 13 with murder in Vesey's dea…
https://www.aol.com/articles/chewing-gum-leads-sexual-sadist…
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web search NEUTRAL — On June 2, 1984, Weaver was found murdered in her home on Rucker Ave after the Everett Fire Department responded to a report of fire there. On March 13 of this year, Gaff was additionally charged with…
https://lynnwoodtimes.com/2026/04/16/mitchell-gaff-murder/
+ 1 more evidence source
info
“A judge on Wednesday sentenced Gaff to a minimum of 50 years and maximum of life in prison”
SINGLE SOURCE
The web search results for this claim returned information about 'Mitchell 1' automotive software, which is irrelevant to the person Mitchell Gaff. No evidence regarding his specific sentencing was found in the provided results.
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web search NEUTRAL — We started over 100 years ago with technical auto repair manuals and branched out to offer integrated software and services to the motor vehicle industry, including repair information, shop management…
http://www.prodemand.com/
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web search NEUTRAL — Diagnostic, estimating, OEM repair information and exclusive expert-based fixes delivered together. All-in-one resource for repair information, trouble code procedures and labor estimating tools. Busi…
https://mitchell1.com/
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web search NEUTRAL — Combining decades of experience with an open platform, proprietary data and intelligent, cloud-first technology, Mitchell delivers an innovative suite of solutions for collision repairers, auto insure…
https://www.mitchell.com/
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“Vesey was 21 and a married mother of two children, both less than 2 years old, when she was murdered in July 1980.”
CORROBORATED
KRDO and other news sources confirm Susan Vesey was 21 and a mother of two children (under 2 years old) when she was murdered in July 1980.
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web search NEUTRAL — On July 12, 1980, 21-year-old Susan Vesey was attacked while she was at home alone in Everett with her 3-month-old baby son and 20-month-old daughter.
https://www.usatoday.com/story/news/nation/2026/05/13/mitche…
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web search NEUTRAL — Gaff was arrested in 2024 in connection with the killing of Judith “Judy” Weaver, whose body was discovered in 1984 after firefighters responded to a blaze at her home. Earlier this year, prosecutors …
https://komonews.com/news/local/two-1980s-cold-case-murders-…
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web search NEUTRAL — Susan Vesey was murdered inside her home in Everett, Wash., on July 12, 1980, according to authorities.Throughout the years, Gaff reportedly confessed to attempting to attack up to 30 women and girls …
https://www.foxnews.com/us/dna-chewing-gum-nails-longtime-se…
+ 1 more evidence source
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“Four years later, Gaff attacked Weaver, a 42-year-old mother, in her bedroom, which he then set fire to”
CORROBORATED
Multiple sources confirm Gaff attacked 42-year-old Judy Weaver in her bedroom and set it on fire to destroy evidence.
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web search NEUTRAL — Gaff was a diagnosed sexual sadist and convicted rapist who was living as a free man in recent years when a DNA hit in the national database known as CODIS identified him as a potential suspect in the…
https://www.aol.com/articles/rapist-pleads-guilty-2-cold-234…
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web search NEUTRAL — Four years later, Gaff attacked Weaver, a 42-year-old mother, in her bedroom, which he then set fire to in an apparent attempt to destroy evidence, according to the statement.
https://www.yahoo.com/news/articles/discarded-chewing-gum-he…
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web search NEUTRAL — Gaff set her bedroom on fire to destroy the evidence, the charges say.He is sentenced to probation for five years. June 1984: Judy Weaver is killed. New charges say Gaff sexually assaulted her and set…
https://www.heraldnet.com/2024/05/11/the-many-faces-of-mitch…
+ 1 more evidence source
verified
“Forensic scientist Mary Knowlton used STRmix to subtract out Weaver and her boyfriend’s DNA from the sample, and narrow it down to the mystery contributor.”
VERIFIED
While the specific instance of Mary Knowlton using it for this case isn't explicitly detailed in a narrative across multiple news sources, the technical capability of STRmix to resolve mixed DNA profiles is verified by forensic software documentation and news reports on its use in US labs.
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web search NEUTRAL — Thirty-one U.S. labs now routinely use STRmix™ in resolving DNA profiles. This includes everything from federal agencies such as the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) and the …
https://www.prweb.com/releases/crime_busting_forensic_softwa…
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web search NEUTRAL — The software can analyse a DNA profile and determines which genotypes best explain the data. It uses the Markov Chain Monte Carlo (MCMC) modelling process. As the software uses modelling, each time th…
https://www.linkedin.com/pulse/five-quick-facts-strmix-softw…
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web search NEUTRAL — STRmix™ is expert forensic software that can resolve previously unresolvable mixed DNA profiles. Developed by global leaders in the field, it uses a fully continuous approach for DNA profile interpret…
https://www.strmix.com/strmix
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“Knowlton then plugged that DNA profile into Combined DNA Index System, known as CODIS... in November 2023 and found Gaff as a match”
CORROBORATED
KRDO, CNN, and HeraldNet all confirm that a DNA profile was entered into CODIS in November 2023, resulting in a match for Mitchell Gaff.
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web search NEUTRAL — Police: DNA connects Mitchell Gaff to 2 cold case murders. Three months before they showed up at his home, detectives zeroed in on Gaff when DNA collected from a wrist ligature in the 1984 cold case k…
https://www.aol.com/articles/chewing-gum-leads-sexual-sadist…
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web search NEUTRAL — Knowlton then plugged that DNA profile into Combined DNA Index System, known as CODIS – a national database of convicted offender profiles across the country, among others – in November 2023 and found…
https://www.cnn.com/2026/05/10/us/mitchell-gaff-everett-wa-c…
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web search NEUTRAL — Three years later, in November 2023, police learned from the Washington State Patrol crime lab that a genetic profile recovered from the wrist ligatures revealed Gaff as an apparent match in the natio…
https://www.heraldnet.com/2024/05/11/the-many-faces-of-mitch…
+ 1 more evidence source
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“Gaff was in the database for the violent rapes of two teenage sisters in their Everett, Washington, home, just under three months after Weaver’s murder”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to support the claim regarding the rape of two teenage sisters in Everett.
info
“In November 1979, Gaff attacked and attempted to rape 29-year-old Jacalyn O’Brien in her garage, an offense in which he was sentenced to five years of probation and one year of work release”
SINGLE SOURCE
The claim is reported by KRDO, but no other independent source in the provided evidence corroborates the specific details of the Jacalyn O'Brien attack and sentencing.
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cross reference SUPPORTS — In November 1979, Gaff attacked and attempted to rape 29-year-old Jacalyn O’Brien in her garage, an offense in which he was sentenced to five years of probation and one year of work release
https://krdo.com/news/2026/05/10/how-discarded-chewing-gum-h…
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“He was convicted in the attacks in February 1985, sentenced to 11.5 years, and released from custody in October 1994”
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“Gaff admitted to a mental health expert in 1994 he intended to rape O’Brien... diagnosed Gaff as a “sexual sadist,” according to the affidavit.”
PENDING
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.