CONTENTS Golden State Killer pg 2
Saltman Saltman Quarterly Quarterly
Carbon Chronicles pg 3
Research Roundup pg 4
Volume | Fall Winter 2020 Volume 12 11| 2019
the future of
FORENSICS
COVER ILLUSTRATION BY CORLY HUANG
SQ INSIDER
Genealogy and the Golden State Killer
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hundred burglarized homes. Children quivering with fear behind closet doors. Violently murdered couples. All the work of one man–California’s most prolific murderer, the Golden State Killer. From 1974 to 1986, police departments along the west coast struggled to keep up with his crimes. The Golden State Killer left no fingerprints and always wore a mask, leaving his surviving victims incapable of identifying him. But he left one crucial piece of evidence: DNA. In 2001, after the development of modern genetic testing, DNA evidence across different crime scenes was used to connect all the crimes to one person. But, the DNA did not match any known person in federal DNA databases. So, how did we finally catch him? The story begins not in a police station, but with the field of genealogy. Genealogy has been used to track family histories for centuries. Recent developments in sequencing technology have allowed researchers to use genetic variation between humans and chromosomal recombination, in addition to family records, to establish ancestry. What is recombination? In humans, sex cells are produced when diploid cells undergo meiosis. During this process, homologous chromosomes line up, break off, and exchange genetic material, causing increased genetic diversity in the daughter cells. Genes around the breakage point on a chromosome become separated and are no longer “linked.” A stretch of genes in a person’s chromosome becomes greatly unlinked by the time their grandchild inherits them, because of the numerous rounds of recombination that occur with every generation. Sequencing an entire section of genes is expensive and time-consuming. As a solution, direct-to-consumer (DTC) companies like AncestryDNA and 23&Me sequence single nucleotide p oly mor phisms (SNPs), which are one-nucleotide variations in the genome. Two people sharing a long stretch of SNPs are closely related, while two people sharing little to no SNPs are distantly related.
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Text & Illustration by
VARSHA RAJESH
In 2010, the public database GEDmatch was created to help people find their relatives. Information purchased from DTC companies can be uploaded as profiles to GEDmatch, which then uses its own algorithms to establish relationships between users. When Detective Paul Holes uploaded the Golden State Killer’s sequenced DNA from the Ventura County rape kit to GEDmatch, more than a hundred profiles came up as relatives. The team took almost four months to construct numerous family trees that narrowed down the pool of suspects to two, one of which was Joseph James DeAngelo, Jr. Suspicious of DeAngelo, a 73 year-old retired cop living in Sacramento County, police discreetly collected his DNA samples from his car doors while conducting surveillance. When tested, this DNA matched that of the crime scene, and the Golden State Killer was finally unmasked. Since then, more than 50 cases have been solved with the help of forensic genealogy, according to NBC. However, the field is expanding at such a rate that investigators, genealogists, and crime labs are operating with minimal restrictions on issues like privacy. After consumers voiced concerns about law enforcement having access to the GEDmatch database and accusing relatives, the company changed their policy to require users to “opt-in” if they wanted their information to appear in searches conducted by law enforcement. However, The Atlantic reports that only 163,000 users of the 1.3 million have opted in, severely restricting the ability of law enforcement to construct complete family trees. Another privacy issue is that anyone can upload DNA with the intention of constructing a suspect pool, and these profiles are extremely hard to track and remove because they are not flagged as law enforcement. Users who opted-out of sharing information with law enforcement could still be considered in these searches. In 2018, DeAngelo was charged with 13 counts of murder, and his preliminary hearing is set for this year. He did not enter a plea. While his trial is still ongoing, forensic genealogical methods have yet to be used as official evidence; in every case so far, offenders have either died prior to the conviction or pled guilty. But the presentation of this technology in a courtroom is inevitable. Solving a 30 year cold case brings peace of mind to countless victims and their families, but at the cost of users who unwittingly upload information that could implicate their relatives. Which one is more important? Currently, our privacy is protected, but a verdict could easily override the status quo.
Editor-in-Chief: Emma Huie Executive Editor: Arya Natarajan Editor-at-Large: Sharada Saraf Production Editors: Zarina Gallardo, Julia Cheng Design: Nicole Anderson, Anvitha Soordelu, Tania Gallardo, Khulan Hoshartsaga Research Editors: Xaver Audhya, Gayathri Kalla, Alejandro Dauguet
Copy Editors: Shreya Shriram, Daniel Lusk, Nikhil Jampana, Andra Thomas Staff Writers: Varsha Rajesh, Mahima Advani Staff Illustrators: Corly Huang, Varsha Rajesh, Cristina Corral Tech Editors: Salma Sheriff, Lynn Nguyen, Juliana Fox, Noorhan Amani, Max Gruber, Rebecca Chen
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Text by MAHIMA ADVANI Illustration by CRISTINA CORRAL Carbon is omnipresent. It appears in our writing utensils, our diamonds, and even our blood. Scientists have manipulated carbon’s ubiquity to develop novel technology, especially in relation to forensic science. Residing at the center of modern radiocarbon dating, this element’s isotopic nature enables us to identify the birth and death years of human remains, answering once-unsolvable crime cases. Carbon-14, one useful form of carbon, has an unequal number of protons and neutrons, forming a radioactive isotope of the usual carbon-12 atom. The Australian Radiation Protection and Nuclear Safety Agency explains the isotopic atom’s instability releases negatively-charged, “high-speed” electrons, or beta particles–these particles can be detected and mark carbon-14 as “radioactive.” Every 5,700 years, half of a given quantity of carbon-14 decays and emits beta particles, according to the National Earth Science Teachers Association. This lengthy half-life, along with the atmosphere’s steady ratio of carbon-14 to carbon-12 is how William Libby, a 20th century physical chemist, discovered radiocarbon dating. Radiocarbon dating allows scientists to identify the age of once-living, carbon-based beings. According to the National Ocean Service, the carbon cycle, a never-ending rotation of carbon from the atmosphere to the Earth, occurs because of our world’s processes–volcanic eruptions, the food web, and much more. All living beings, as part of this carbon cycle, reflect the atmosphere’s constant carbon-14 to carbon-12 ratio. However, carbon-14 decays after an individual’s passing; each half-life decreases the carbon-14 to carbon-12 ratio, and technology can identify the age of the remains. To quantify decayed carbon-14, scientists burn a piece of remains and count the number of beta particles released. Comparing the
ratio of carbons in the remains to the atmosphere’s ratio reveals the remains’ age. This technology initialized a “radioactive revolution” in paleontology, archaeology, and our Earth’s history. As carbon dating transformed fossils and rocks into natural “time capsules,” scientists no longer relied upon misleading geological layers to establish chronology of events. According to the American Chemical Society, the carbon ratio in certain artifacts even revealed multiple origin sites of human civilization, contradicting previous beliefs of only European origins. Prior to the 1950s, radiocarbon dating identified artifacts from 500 to 50,000 years old. However, as the National Institute of Justice reveals, nuclear weapons usage fluctuated atmospheric radiocarbon amounts post mid-20th century. This seemingly unrelated political event led to modern developments in radiocarbon dating–the amount of radiocarbon in a once-living being’s tissues now corresponded with this specific time’s atmospheric radiocarbon content. This newfound ability to analyze remains at a finer time scale expanded the boundaries of human remains analysis and crime scene work–a victory for the forensic science community. Forensic scientists frequently use radiocarbon dating to identify birth and death years of corpses. Body parts that emerge early in a human’s life, like tooth enamel, reflect the atmospheric amount of radiocarbon at their time of formation,correlating with the birth year of a once-living being. However, body parts that regenerate more, like nails or tissues, correlate with current atmospheric
radiocarbon levels and can identify one’s death year. Such techniques provide new perspectives to older, unresolved cases. One cold case involved the discovery of a child’s skull in 1968 near a Canadian river. According to a paper published in the Journal of Forensic Sciences, anthropologists first estimated the child’s age to be seven to nine years, which did not match any missing children at the time. However, in 2005, scientists reopened the case with modern forensic science methods. Dental material analysis indicated that the birth year was around 1960, with death about four to five years later, rather than seven to nine. The discovered cranium was connected with a missing child from over 40 years ago by revealing the correct age and death year– thus, solving the once unsolvable. However, this technique also has its limitations. Nuclear weapons in World War II and the Nuclear-Test Ban Treaty in 1963 restored atmospheric radiocarbon levels closer to the initial constant ratio. These events may prevent future scientists from telling the age difference between remains using radiocarbon dating—a disappointing conclusion to a revolutionary scientific development. Understanding how carbon’s chemistry interacts with living beings and the carbon cycle, or how a human’s anatomy can identify birth or death years, reveals forensic science’s close relationship to chemical and biological phenomena. Even political events, which emphasize modern radiocarbon dating’s problematic dependence on nuclear testing, control biological developments in unpredictable ways. Modern radiocarbon dating’s relevance has been established by not only solved unsolvable cases, but also by revealing the ever-growing influence and intersectionality of forensic science.
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SQ INSIDER
Research Roundup: Forensics Curated by SQ Research Editors and Executive Staff
Breaking Bad Blood: Tracing Victim Age by Forensic Spectroscopy Following a crime, scientists carry out different tests to collect evidence and infer what occurred. However, many of these often cannot be performed at the scene, produce unreliable results, and/or take a long time–the last being extremely important in following a fresh trail. Among these tests is blood spatter analysis, which has traditionally been used to determine the details of a crime, such as the force of a blow or the angle of attack. Recently, scientists at the University of Albany, State University of New York have developed a new type of blood spatter analysis that uses light radiation to help determine the age group of the victim or suspect. The proportion or distinct proteins in blood produces a distinct signature that differs across age groups. In only a few hours, this technique can contribute data on age to help form a more complete physical trait profile. While for now this experiment acts a proof-of-concept, one day this technique may be further developed and help investigators track down the culprits in a shorter time-frame.
RhiNo Getting Away: Fighting Poaching by Genetically Matching Ivory Increased hunting has decimated the population of black and white African rhinoceros over the last two centuries. Despite legal efforts, trade of rhino tusks on the black market continues– as a result, wildlife specialists and genetic scientists have teamed up to track down those responsible. With the help of law enforcement, a genetic database known as the Rhinoceros DNA Index System has been developed to trace poaching evidence to individual rhinos. By analyzing the frequency of repetitive DNA nucleotide sequences in confiscated rhino tusks and tissue, scientists can identify forensic matches and trace the underground distribution and sale of rhino ivory back to the poaching of the animal itself. As a result, scores of rhino poaching cases have been solved in South Africa, where rhinoceros poaching is rife, adding forensics to the arsenal of tools used in combating crimes against wildlife.
Paper: Differentiating Donor Age Groups Based on Raman Spectroscopy of Bloodstain for Forensic Purposes Authors: Doty KC, Lednev IK Journal: ACS Central Science
A Blast from the Past: Shedding Light on Ancient Injury Paper: State of the art forensic techniques reveal evidence of interpersonal violence ca. 30,000 years ago Authors: Kranioti EF, Grigorescu D, Havarti K Journal: PLOS One
In the early 1940s, while exploring a Transylvanian cave, archaeologists discovered the skull of a man who lived approximately 33,000 years ago. Two fractures were found in the skull, and for decades, researchers have wondered what might have caused them–was it a bludgeoning, or did the damage occur after death? Using modern forensic methods, scientists from the University of Crete may have solved this cold case. By employing computed tomography, a technique that uses X-rays to create cross-sections of an object that can then be used to make a virtual 3D reconstruction, they were able to see new details such as a rounded wound site, a pattern of fractures associated with assault, and remnant bone chips. These characteristics are only present if soft tissue existed at the time of injury, allowing the researchers to determine that the injuries occurred before death. The results suggest a club-like tool ultimately dealt the fatal blows–a morbid snapshot of a violent incident during the Upper Paleolithic period. In effect, the findings garnered by this grisly episode of prehistoric violence are testament to the utility of forensics in solving modern crimes by means of historical patterns. Paper: Robust forensic matching of confiscated horns to individual poached African rhinoceros Authors: Harper C et al. Journal: Current Biology
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