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Category Archives: General Forensics

Criminal Mischief: Episode #27: ABO Blood Typing

Criminal Mischief: Episode #27: ABO Blood Typing

 

LISTEN: https://soundcloud.com/authorsontheair/27-abo-blood-typing

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

SHOW NOTES: http://www.dplylemd.com/criminal-mischief-notes/27-abo-blood-typing.html

 

ABO Blood Type System

From FORENSICS FOR DUMMIES

By simply typing the blood at a crime scene, investigators narrow their suspect list and completely exonerate some suspects by using the population distribution information for the four ABO blood types. 

Population Distribution of ABO Blood Types

O: 43%

A: 42%

B: 12%

AB: 3%

Besides determining the ABO type, serologists are able to further individualize blood samples. RBCs contain more proteins, enzymes, and antigens than those used in the ABO classification system. These include antigens with such catchy names as Duffy, Kell, and Kidd and intracellular enzymes such as adenylate kinase, erythrocyte acid phosphatase, and the very useful phosphoglucomutase (PGM).

PGM is an enzyme that appears in many different forms, or isoenzymes, and at least ten of them are fairly common. Regardless of ABO type, a particular individual can have any combination of the isoenzymes of PGM. The ME and the serologist use that fact to further narrow the list of suspects for further DNA analyses and confirmation that they were capable of leaving a particular bloodstain.

For example, say that a stain is Type AB and has PGM 2. The ME knows the AB blood type is found in only 3 percent (see Table 14‐1) of the population, and PGM 2 is found in only 6 percent of people. Because these two factors are inherited independently, the probability of a particular individual being Type AB, PGM 2 is only 0.18 percent or less than 2 per 1,000. 

If the police find blood at the scene that matches the blood of a suspect who has Type AB, PGM 2 blood, the probability that that suspect is not the perpetrator is 2 in 1,000. Although not perfect, those odds still are much better than a coin toss. 

Testing for Paternity 

You inherit your blood type from your parents. For that reason, a serologist can assess paternity in many cases. The crime lab is often involved in paternity testing because paternity may be a critical component in determining child support, custody, and visitation. It also may play an important role in crimes and civil proceedings that involve kidnappings, insurance fraud, and inheritance conflicts. 

Inheriting your blood type 

ABO blood types, or phenotypes, come in only four varieties: A, B, AB, and O. But, for some blood types two genotypes, or gene pairings, are possible. A phenotype is what something looks like (in this case the ABO blood type), while the genotype is the underlying genetic pattern. We receive our ABO genes from our parents, one from Dad and one from Mom. 

The important thing to know in this system is that A and B genes are co-dominant (equally dominant), while the O gene is recessive. So someone who receives an A gene from one parent and an O gene from the other has Type A blood, but not Type O, because the A gene is dominant. 

Determining Possible Genotypes from Phenotypes 

Type A: AA or AO

Type B: BB or BO

Type AB: AB

Type O: OO

People with Type O blood must have an OO genotype. They can have neither an A nor a B gene because having one or the other dominates the O gene and produces either Type A or Type B blood. 

A person with Type A blood can either receive an A gene from each parent and thus have an AA genotype or an A gene from one parent and an O gene from the other for an AO genotype. Remember, A is dominant, so when it is paired with the recessive O gene, the A gene determines blood type. People with the AA and AO genotypes both have Type A blood, but genetically speaking, they’re different. 

Type A parents who have AA genotypes can provide only A genes to their offspring, because all their eggs or sperm have an A gene. But Type A parents who have AO genotypes can provide either an A gene or an O gene to their offspring, because half their eggs or sperm have an A gene, and the other half have an O gene. When both parents are Type A, several possibilities exist for the genotype their offspring will have.

In each of the scenarios presented in Figure 14‐1, the child’s blood type is Type A, except when both parents donate an O gene. In the latter case, the child’s genotype and blood type (phenotype) respectively are OO and Type O. These parents can’t have any offspring who have Type B phenotype or BB, BO, or AB genotypes, because neither parent has a B gene to donate. 

Determining Fatherhood

Blood typing can exclude paternity but cannot absolutely verify it. For example, a man with Type AB blood can’t father a child with Type O blood. So if a child has Type O blood, all men with the Type AB are ruled out as the child’s father. A man with Type A (genotypes AA or AO) blood can be the father, but only if he has an AO genotype. Men who have AA genotypes also are excluded. Men with the AO genotype, however, can’t be ruled out at this point. 

To dig deeper into this complex system grab a copy of either:

FORENSICS FOR DUMMIES: http://www.dplylemd.com/book-details/forensics-for-dummies.html

 

HOWDUNNIT: FORENSICS: http://www.dplylemd.com/book-details/howdunnit-forensics.html

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Criminal Mischief: Episode #25: A Stroll Through Forensic Science History

 

Criminal Mischief: Episode #25: A Stroll Through Forensic Science History

 

 

LISTEN:https://soundcloud.com/authorsontheair/forensicsciencehistory

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

SHOW NOTES: http://www.dplylemd.com/criminal-mischief-notes/25-a-stroll-through-forensi.html

 

FORENSIC SCIENCE TIMELINE 

Prehistory: Early cave artists and pot makers “sign” their works with a paint or impressed finger or thumbprint.

1000 b.c.: Chinese use fingerprints to “sign” legal documents.

3rd century BC.: Erasistratus (c. 304–250 b.c.) and Herophilus (c. 335–280 b.c.) perform the first autopsies in Alexandria.

2nd century AD.: Galen (131–200 a.d.), physician to Roman gladiators, dissects both animal and humans to search for the causes of disease.

c. 1000: Roman attorney Quintilian shows that a bloody handprint was intended to frame a blind man for his mother’s murder.

1194: King Richard Plantagenet (1157–1199) officially creates the position of coroner.

1200s: First forensic autopsies are done at the University of Bologna.

1247: Sung Tz’u publishes Hsi Yuan Lu (The Washing Away of Wrongs), the first forensic text.

c. 1348–1350: Pope Clement VI(1291–1352) orders autopsies on victims of the Black Death to hopefully find a cause for the plague.

Late 1400s: Medical schools are established in Padua and Bologna.

1500s: Ambroise Paré (1510–1590) writes extensively on the anatomy of war and homicidal wounds.

1642: University of Leipzig offers the first courses in forensic medicine.

1683: Antony van Leeuwenhoek (1632–1723) employs a microscope to first see living bacteria, which he calls animalcules.

Late 1600s: Giovanni Morgagni (1682–1771) first correlates autopsy findings to various diseases.

1685: Marcello Malpighi first recognizes fingerprint patterns and uses the terms loops and whorls.

1775: Paul Revere recognizes dentures he had made for his friend Dr. Joseph Warren and thus identifies the doctor’s body in a mass grave at Bunker Hill.

1775: Carl Wilhelm Scheele (1742–1786) develops the first test for arsenic.

1784: In what is perhaps the first ballistic comparison, John Toms is convicted of murder based on the match of paper wadding removed from the victim’s wound with paper found in Tom’s pocket.

1787: Johann Metzger develops a method for isolating arsenic.

c. 1800: Franz Joseph Gall (1758–1828) develops the field of phrenology.

1806: Valentine Rose recovers arsenic from a human body.

1813: Mathieu Joseph Bonaventure Orfila (1787–1853) publishes Traité des poisons (Treatise on Poison), the first toxicology textbook. 

1821: Sevillas isolates arsenic from human stomach contents and urine, giving birth to the field of forensic toxicology.

1823: Johannes Purkinje (1787–1869) devises the first crude fingerprint classification system.

1835: Henry Goddard (1866–1957) matches two bullets to show they came from the same bullet mould.

1836: Alfred Swaine Taylor (1806–1880) develops first test for arsenic in human tissue.

1836: James Marsh (1794–1846) develops a sensitive test for arsenic (Marsh test).

1853: Ludwig Teichmann (1823–1895) develops the hematin test to test blood for the presence of the characteristic rhomboid crystals.

1858: In Bengal, India, Sir William Herschel (1833–1917) requires natives sign contracts with a hand imprint and shows that fingerprints did not change over a fifty-year period.

1862: Izaak van Deen (1804–1869) develops the guaiac test for blood.

1863: Christian Friedrich Schönbein (1799–1868) develops the hydrogen peroxide test for blood.

1868: Friedrich Miescher (1844–1895) discovers DNA.

1875: Wilhelm Konrad Röntgen (1845–1923) discovers X-rays.

1876: Cesare Lombroso (1835–1909) publishes The Criminal Man, which states that criminals can be identified and classified by their physical characteristics.

1877: Medical examiner system is established in Massachusetts.

1880: Henry Faulds (1843–1930) shows that powder dusting will expose latent fingerprints.

1882: Alphonse Bertillon (1853–1914) develops his anthropometric identification system.

1883: Mark Twain (1835–1910) employs fingerprint identification in his books Life on the Mississippi and The Tragedy of Pudd’nhead Wilson (1893– 1894).

1887: In Sir Arthur Conan Doyle’s first Sherlock Holmes novel, A Study in Scarlet, Holmes develops a chemical to determine whether a stain was blood or not—something that had not yet been done in a real-life investigation.

1889: Alexandre Lacassagne (1843–1924) shows that marks on bullets could be matched to those within a rifled gun barrel.

1892: Sir Francis Galton (1822–1911) publishes his classic textbook Finger Prints. 

1892: In Argentina, Juan Vucetich (1858–1925) devises a usable fingerprint classification system. 

1892: In Argentina, Francisca Rojas becomes the first person charged with a crime on fingerprint evidence.

1898: Paul Jeserich (1854–1927) uses a microscope for ballistic comparison. 

1899: Sir Edward Richard Henry (1850–1931) devises a fingerprint classification system that is the basis for those used in Britain and America today.

1901: Karl Landsteiner (1868–1943) delineates the ABO blood typing system. 

1901: Paul Uhlenhuth (1870–1957) devises a method to distinguish between human and animal blood. 

1901: Sir Edward Richard Henry becomes head of Scotland Yard and adopts a fingerprint identification system in place of anthropometry. 

1902: Harry Jackson becomes the first person in England to be convicted by fingerprint evidence. 

1910: Edmund Locard (1877–1966) opens the first forensic laboratory in Lyon, France. 

1910: Thomas Jennings becomes the first U.S. citizen convicted of a crime by use of fingerprints.

1915: Leone Lattes (1887–1954) develops a method for ABO typing dried bloodstains.

1920: The Sacco and Vanzetti case brings ballistics to the public’s attention. The case highlights the value of the newly developed comparison microscope.

1923: Los Angeles Police Chief August Vollmer (1876–1955) establishes the first forensic laboratory. 

1929: The ballistic analyses used to solve the famous St. Valentine’s Day Massacre in Chicago lead to the establishment of the Scientific Crime Detection Laboratory (SCDL), the first independent crime lab, at Northwestern University.

1932: FBI’s forensic laboratory is established.

1953: James Watson (1928– ), Francis Crick (1916–2004), and Maurice Wilkins (1916–2004) identify DNA’s double-helical structure. 

1954: Indiana State Police Captain R.F. Borkenstein develops the breathalyzer. 

1971: William Bass establishes the Body Farm at the University of Tennessee in Knoxville.

1974: Detection of gunshot residue by SEM/EDS is developed. 

1977: FBI institutes the Automated Fingerprint Identification System (AFIS). 

1984: Sir Alec Jeffreys (1950– ) develops the DNA “fingerprint” technique.

1987: In England, Colin Pitchfork becomes the first criminal identified by the use of DNA.

1987: First United States use of DNA for a conviction in the Florida case of Tommy Lee Andrews.

1990: The Combined DNA Index System (CODIS) is established.

1992: The polymerase chain reaction (PCR) technique is introduced.

1994: The DNA analysis of short tandem repeats (STRs) is introduced. 

1996: Mitochondrial DNA is first admitted into a U.S. court in Tennessee v. Ware. 

1998: The National DNA Index System (NDIS) becomes operational.

Since then:

Touch DNA

Familial DNA

Phenotypic DNA

 

Talking About Forensic Science on the For Dummies Podcast Series

 

Had I a great time chatting with Eric Martsolf on the For Dummies podcast series about FORENSICS FOR DUMMIES and Forensic Science. Drop by and take a listen:

http://fordummiesthepodcast.twa.libsynpro.com/for-dummies-the-podcast-forensics

More Info and to order FORENSICS FRO DUMMIES:
http://www.dplylemd.com/book-details/forensics-for-dummies.html

 

 

 

 

Criminal Mischief: The Art and Science of Crime Fiction: Episode #17: DNA and Twins

DNA Replication

 

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-17-dna-and-identical-twins

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

SHOW NOTES:

For years it was felt that the DNA of identical twins was indeed identical. Since they come from a single fertilized egg, this would seem intuitive. But, nature likes to throw curve balls—and the occasional slider. After that first division of the fertilized, and after the two daughter cells go their way toward producing identical humans, things change. And therein lies the genetic differences between two “identical” twins.

LINKS:

One Twin Committed the Crime—but Which One?: https://www.nytimes.com/2019/03/01/science/twins-dna-crime-paternity.html

The Claim: Identical Twins Have Identical DNA: https://www.nytimes.com/2008/03/11/health/11real.html

The Genetic Relationship Between Identical Twins: https://www.verywellfamily.com/identical-twins-and-dna-2447117

Identical Twins’ Genes Are Not Identical: https://www.scientificamerican.com/article/identical-twins-genes-are-not-identical/

Rare Australian Twins Are “Semi-Identical,: Sharing 89 Percent of Their DNA: https://www.inverse.com/article/53633-semi-identical-twins-share-78-percent-of-dna

 

Criminal Mischief: Episode #16: Arsenic: An Historical and Modern Poison

Arsenic

Criminal Mischief: Episode #16: Arsenic: An Historical and Modern Poison

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-15-arsenic-an-historical-and-modern-poison

SHOW NOTES: http://www.dplylemd.com/criminal-mischief-notes/16-arsenic-an-historical.html

PAST SHOWS: http://www.dplylemd.com/criminal-mischief.html

Howdunnit200X267

From HOWDUNNIT:FORENSICS

Toxicology is a relatively new science that stands on the shoulders of its predecessors: anatomy, physiology, chemistry, and medicine. Our knowledge in these sciences had to reach a certain level of sophistication before toxicology could become a reality. It slowly evolved over more than two hundred years of testing, starting with tests for arsenic. 

Arsenic had been a common poison for centuries, but there was no way to prove that arsenic was the culprit in a suspicious death. Scientist had to isolate and then identify arsenic trioxide—the most common toxic form of arsenic— in the human body before arsenic poisoning became a provable cause of death. The steps that led to a reliable test for arsenic are indicative of how many toxicological procedures developed. 

1775: Swedish chemist Carl Wilhelm Scheele (1742–1786) showed that chlorine water would convert arsenic into arsenic acid. He then added metallic zinc and heated the mixture to release arsine gas. When this gas contacted a cold vessel, arsenic would collect on the vessel’s surface. 

1787: Johann Metzger (1739–1805) showed that if arsenic were heated with charcoal, a shiny, black “arsenic mirror” would form on the charcoal’s surface. 

1806: Valentine Rose discovered that arsenic could be uncovered in the human body. If the stomach contents of victims of arsenic poisoning are treated with potassium carbonate, calcium oxide, and nitric acid, arsenic trioxide results. This could then be tested and confirmed by Metzger’s test. 

1813: French chemist Mathieu Joseph Bonaventure Orfila (1787–1853) developed a method for isolating arsenic from dog tissues. He also published the first toxicological text, Traité des poisons (Treatise on Poison), which helped establish toxicology as a true science. 

1821: Sevillas used similar techniques to find arsenic in the stomach and urine of individuals who had been poisoned. This is marked as the beginning of the field of forensic toxicology. 

1836: Dr. Alfred Swaine Taylor (1806–1880) developed the first test for arsenic in human tissue. He taught chemistry at Grey’s Medical School in England and is credited with establishing the field of forensic toxicology as a medical specialty. 

1836: James Marsh (1794–1846) developed an easier and more sensitive version of Metzger’s original test, in which the “arsenic mirror” was collected on a plate of glass or porcelain. The Marsh test became the standard, and its principles were the basis of the more modern method known as the Reinsch test, which we will look at later in this chapter. 

As you can see, each step in developing a useful testing procedure for arsenic stands on what discoveries came before. That’s the way science works. Step by step, investigators use what others have discovered to discover even more. 

Acute vs. Chronic Poisoning 

At times the toxicologist is asked to determine whether a poisoning is acute or chronic. A good example is arsenic, which can kill if given in a single large dose or if given in repeated smaller doses over weeks or months. In either case, the blood level could be high. But the determination of whether the poisoning was acute or chronic may be extremely important. If acute, the suspect list may be long. If chronic, the suspect list would include only those who had long-term contact with the victim, such as a family member, a caretaker, or a family cook. 

So, how does the toxicologist make this determination? 

In acute arsenic poisoning, the ME would expect to find high levels of arsenic in the stomach and the blood, as well as evidence of corrosion and bleeding in the stomach and intestines, as these are commonly seen in acute arsenic ingestion. If he found little or no arsenic in the stomach and no evidence of acute injury in the gastrointestinal (GI) tract, but high arsenic levels in the blood and tissues, he might suspect that the poisoning was chronic in nature. Here, an analysis of the victim’s hair can be invaluable. 

Hair analysis for arsenic (and several other toxins) can reveal exposure to arsenic and also give a timeline of the exposure. The reason this is possible is that arsenic is deposited in the cells of the hair follicles in proportion to the blood level of the arsenic at the time the cell was produced. 

In hair growth, the cells of the hair’s follicle undergo change, lose their nuclei, and are incorporated into the growing hair shaft. New follicular cells are produced to replace them and this cycle continues throughout life. Follicular cells produced while the blood levels of arsenic are high contain the poison, and as they are incorporated into the hair shaft the arsenic is, too. On the other hand, any follicular cells that appeared while the arsenic levels were low contain little or no arsenic. 

In general, hair grows about a half inch per month. This means that the toxicologist can cut the hair into short segments, measure the arsenic level in each, and reveal a timeline for arsenic exposure in the victim. 

Let’s suppose that a wife, who prepares all the family meals, slowly poisoned her husband with arsenic. She began by adding small amounts of the poison to his food in February and continued until his death in July. In May he was hospitalized with gastrointestinal complaints such as nausea, vomiting, and weight loss (all symptoms of arsenic poisoning). No diagnosis was made, but since he was doing better after ten days in the hospital, he was sent home. Such a circumstance is not unusual since these types of gastrointestinal symptoms are common and arsenic poisoning is rare. Physicians rarely think of it and test for it. After returning home, the unfortunate husband once again fell ill and finally died. 

As part of the autopsy procedure, the toxicologist might test the victim’s hair for toxins, and if he did, he would find the arsenic. He could then section and test the hair to determine the arsenic level essentially month by month. If the victim’s hair was three inches long, the half inch closest to the scalp would represent July, the next half inch June, the next May, and so on until the last half inch would reflect his exposure to arsenic in February, the month his poisoning began. Arsenic levels are expressed in parts per million (ppm).

An analysis might reveal a pattern like that seen in Figure 11-1. 

IMAGE in HOWDUNNIT: FORENSICS

 The toxicologist would look at this timeline of exposure and likely determine that the exposure occurred in the victim’s home. The police would then have a few questions for the wife and would likely obtain a search warrant to look for arsenic within the home. 

LINKS: 

Arsenic Poisoning (2007): CA Poison Control: https://calpoison.org/news/arsenic-poisoning-2007

Arsenic Poisoning Cases Wikipedia: https://en.wikipedia.org/wiki/Arsenic_poisoning_cases

Arsenic” a Murderous History: https://www.dartmouth.edu/~toxmetal/arsenic/history.html

Facts About Arsenic: LiveScience: https://www.livescience.com/29522-arsenic.html

Poison: Who Killed Napolean?: https://www.amnh.org/explore/news-blogs/on-exhibit-posts/poison-what-killed-napoleon

Victorian Poisoners: https://www.historic-uk.com/HistoryUK/HistoryofEngland/Victorian-Poisoners/

12 Female Poisoners Who Killed With Arsenic: http://mentalfloss.com/article/72351/12-female-poisoners-who-killed-arsenic

 

 

Criminal Mischief: Episode #06: Is It Harder To Write Crime Fiction Today?

AOTA Graphic

 

Criminal Mischief: Episode #06: Is It Harder To Write Crime Fiction Today?

LISTEN: https://soundcloud.com/authorsontheair/criminal-mischief-episode-06-is-it-harder-to-write-crime-fiction-today

Is It Harder To Write Crime Fiction Today? Notes:

Do modern forensic science and police investigative techniques make creating compelling crime fiction more difficult? Are there simply too many balls to keep in the air? Too much to consider? Or is now little different from then?

The Past, the present, and the future

Forensic Science timeline—-a fairly new discipline

Basic Science, then Medicine, finally forensic science

Personal ID

Visual
Bertillon
West Case
Facial recognition
Behavioral Profiling

Prints, ABO type, DNA, DNA Phenotype

Fingerprints—-then and now

Vucetich—the Rojas case
Stella Nickell Case
Touch DNA
Touch Toxicology

Toxicology

From arsenic to GC/MS

Blood Typing

ABO can exclude but not ID

DNA

Nuclear
Mitochondrial
Familial—Grim Sleeper case
Phenotypic Analysis

Electronics

Cell phones, computers, emails, texts, VMs

LINKS: 

Forensic Science Timeline: http://www.dplylemd.com/articles/forensic-science-timeline.html

History of Fingerprints: http://onin.com/fp/fphistory.html

Brief History of Poisons and Forensic Toxicology: https://www.okorieokorocha.com/poisons-and-forensic-toxicology/

History of Forensic Ballistics: https://ifflab.org/the-history-of-forensic-ballistics-ballistic-fingerprinting/

FORENSICS FOR DUMMIES: http://www.dplylemd.com/book-details/forensics-for-dummies.html

HOWDUNNIT:FORENSICS: http://www.dplylemd.com/book-details/howdunnit-forensics.html

Stella Nickell Wikipedia: https://en.wikipedia.org/wiki/Stella_Nickell

DNA Profiling: https://en.wikipedia.org/wiki/DNA_profiling

Mitochondrial DNA: http://www.dplylemd.com/articles/mitochondrial-dna.html

Familial DNA: http://www.dnaforensics.com/familialsearches.aspx

Grim Sleeper/Lonnie Franklin case: https://en.wikipedia.org/wiki/Grim_Sleeper

Is DNA Phenotyping Accurate: https://www.smithsonianmag.com/innovation/how-accurately-can-scientists-reconstruct-persons-face-from-dna-180968951/

DNA Phenotyping Examples: https://snapshot.parabon-nanolabs.com/examples

Bertillon and the West Brothers: http://www.nleomf.org/museum/news/newsletters/online-insider/november-2011/bertillon-system-criminal-identification.html

 

Does Your DNA Contain Your Image?

DNA-Based Sketches

 

To say that DNA had revolutionized criminal investigations would be a huge understatement. Prior to DNA profiling, identifying a suspect with absolute certainty was more difficult. Fingerprints would work, of course, and eyewitness accounts, though flawed in many ways, could also help. But a criminal leaving behind biological evidence such as blood, semen, saliva, hair, skin cells, and other little bits, offers a method of identity that is second to none. DNA profiling has been used to catch many a criminal. But, in order for it to do its work, there must be something for the DNA analyst to compare the crime scene sample against. The DNA database, CODIS, helps because it stores millions of DNA profiles and if the perpetrator is in the system, a match can be made. But if he is not, the database is of little help.

DNA analysis can reveal the gender of the person who left behind the sample quite easily. But our DNA controls more than that. It determines how tall we will be, what our hair and eye color will be, our intellectual level, our ability to play music, and many other things. Familial DNA has been used to narrow down unknown samples to a smaller group, such as an extended family. And lately, this is been used in conjunction with the various ancestral databases to solve some crimes. But a newer technique offers another tool on the DNA front. It’s called DNA Phenotyping.

The principle seems simple: Since our DNA determines what we look like, would it not be possible to take a DNA sample and then create an image of the individual it belonged to? Maybe. At least great strides have been made in that regard. A case in point is that of research biologist Le Bich-Thuy, who was raped, battered, and strangled 24 years ago. DNA obtained from that scene was subjected to DNA Phenotyping and an image of the individual who likely perpetrated the crime was generated. Not only that, the image was age altered so that it would more accurately reflect what he might look like now. Fascinating case.

 
 
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