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Category Archives: General Forensics

Criminal Mischief on Hiatus Through the Holidays

Criminal Mischief on Hiatus Through the Holidays

 

Criminal Mischief: The Art and Science of Crime Fiction will take a break over the holidays but will be back in January with a three-part series on forensic toxicology. In the meantime, catch up on the 31 past shows:

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

Or spend the holidays improving your forensic science knowledge:

 

FORENSICS FOR DUMMIES

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

 

HOWDUNNIT:FORENSICS

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

 

 

Criminal Mischief: Episode #31: Body Disposal Isn’t Easy

Criminal Mischief: Episode #31: Body Disposal Isn’t Easy

LISTEN: https://soundcloud.com/authorsontheair/episode-31-body-disposal-isnt-easy

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

SHOW NOTES: http://www.dplylemd.com/criminal-mischief-notes/31-body-disposal.html

Details/Order: http://www.dplylemd.com/book-details/howdunnit-forensics.html

From HOWDUNNIT:FORENSICS:

GETTING RID OF THE BODY 

Some criminals attempt to destroy corpses, the primary pieces of evidence in homicides. They think that if the police never find the body, they can’t be convicted. This isn’t true, since convictions have in many cases been obtained when no body is found. And destroying a body is no easy task. 

Fire seems to be the favorite tool for this effort. Fortunately, this is essentially never successful. Short of a crematorium, it is nearly impossible to create a fire that burns hot enough or long enough to destroy a human corpse. Cremation uses temperatures of around 1,500oF for two hours or more and still bone fragments and teeth survive. A torched building would rarely reach these temperatures and would not burn for this long. The body inside may be severely charred on the surface, but the inner tissues and internal organs are often very well preserved. 

Another favorite is quicklime. Murderers use this because they have seen it in the movies and because they don’t typically have degrees in chemistry. If they did, they might think twice about this one. Not that quicklime won’t destroy a corpse; it just takes a long time and a lot of the chemical. Most killers who use this method simply dump some on the corpse and bury it, thinking the lime will do its work and nothing will remain. Quicklime is calcium oxide. When it contacts water, as it often does in burial sites, it reacts with the water to make calcium hydroxide, also known as slaked lime. This corrosive material may damage the corpse, but the heat produced from this activity will kill many of the putrefying bacteria and dehydrate the body. This conspires to prevent decay and promote mummification. Thus, the use of quicklime may actually help preserve the body. 

Acids are also used in this regard, and once again the criminal hopes the acid will completely dissolve the body. Serial killer Jeffrey Dahmer tried this with little success. Indeed, powerful acids such as hydrochloric acid (HCl), sulfuric acid (H2SO4), and
chlorosulfuric acid (HClSO3) can destroy a corpse, bones and all. If enough acid is used over a sufficient period of time, that is. But this is not only difficult but also extremely hazardous. The acids will indeed destroy the corpse, but they will also “eat” the tub the body is in and chew up the plumbing. Acid fumes will peel the wallpaper and burn the perpetrator’s skin, eyes, and lungs. 

FORENSIC CASE FILES: THE ACID BATH MURDERER 

John George Haigh came to the English public’s attention in the 1940s when he confessed to not only multiple murders, but also to drinking his victims’ blood and destroying their corpses with acid. He seemed to favor sulfuric acid, which he kept in a vat in his workshop. He took the victims’ money and, through forgery, their property and businesses, and then basically laughed at the police as he admitted to the killings, believing they could not prosecute him without a corpse. He was wrong. He was convicted through forensic evidence and was hanged at Wandsworth Prison on August 10, 1949. 

So, whether it’s Mother Nature or the work of the perpetrator, something almost always remains for the ME and the other forensic scientist to work with. It may be an intact body, a partially destroyed corpse, or a single bone, but it will give them something to use in identification. Let’s take a look at how they do this—first with a body and then with only skeletal remains

BODY LOCATION 

With the exception of some photographic comparisons, all these forensic identification techniques require a corpse or skeletal remains. No body, nothing to work with. Often a discovered body is what instigates this identification process. But sometimes, investigators know a homicide has occurred, or has likely occurred, but they can’t find the corpse. The Laci Peterson case is an example. When Laci, who was eight months pregnant at the time, went missing on Christmas Eve 2002, in Modesto, California, it was not long before it became obvious that she had been murdered. Authorities launched a search of her neighborhood and the bay where her husband, Scott, had been fishing. In April 2003, the bodies of Laci and her unborn son Conner washed up on shore in San Francisco Bay. Scott Peterson was later convicted of the double murder. 

In homicides, finding and examining the corpse is critical. Searchers use a number of low- and high-tech location methods. All evidence is used to narrow the search area, including the victim’s work and leisure habits and witness statements. The victim may work several miles from home, so searching along this route would be undertaken. Maybe he frequently ran or walked in a nearby wooded area. Or maybe the suspect’s vehicle was spotted or some of the victim’s clothing was found in a remote area. These bits of information can greatly focus the search. 

One basic rule is to “look downhill” for a burial site. Let’s say it is believed that the body in question was buried near a remote roadway. In the area, the terrain rises above the road on one side and falls away on the other. Search downhill. Why? It is much easier to carry a body downhill than up. It’s just that simple. 

Once the area of search has been defined, a systematic approach to cover- ing the area should be followed. Freshly turned dirt, trenches, elevations or depressions in the terrain may be helpful. Fresh graves tend to be elevated above the surrounding area, while older ones may be depressed. This is due to settling of the soil, decay of the body, and collapse of the skeleton. Interestingly, the depth of the depression is greater if the body is deeply buried. This is likely due to the larger amount of turned dirt, which is subject to a greater degree of settling. Another factor could be that in deeper graves, the increased weight of the dirt over the corpse causes earlier and more complete skeletal collapse. 

Tracking dogs, if provided with an article of the victim’s clothing, may be able to follow a scent trail to the burial site. Specially trained cadaver dogs search for the scent of decaying flesh. They can often locate bodies in shallow graves or in water. Deeper graves may present problems.

Another important clue may come from changes in the vegetation over the gravesite. The turning of the soil in the digging process and the presence of the body change the soil conditions in the area over the grave. Changes in compaction, moisture, aeration, and temperature may attract plant species that differ from those around the grave. Or, the plants typical for the area may be present but the changed soil conditions may increase the thickness and richness of their growth. This may be visible, particularly from the air. 

Aerial reconnaissance and photography can be coupled with thermal imaging. Freshly turned dirt loses heat faster than normally compacted soil; it appears “colder” by such a device. Alternatively, a decaying body releases heat, which may reveal a measurable difference when compared to the surrounding area. So, the thermal images are inspected for either cold or warm spots, and these areas are then subjected to a more aggressive search. 

If a suspect area such as a mound or depression is found, special devices that locate sources of heat and nitrogen, both byproducts of the decay process, or that measure changes in the physical properties of the soil, may be employed. Ground-penetrating radar can “see” into the ground and often locate a buried body. Measurement of the electrical conductivity may prove helpful— a buried body often adds moisture to the soil, and the moisture increases the soil’s electrical conductivity. Two metal probes are placed in the soil, and an electrical current is passed between them and measured. Changes in this current may indicate where the body is buried. 

Magnetic devices may also be employed. A simple metal detector may locate the victim’s jewelry or belt buckle. 

A special device called a magnetometer, which measures the magnetic properties of soil, can also be helpful. Soil contains small amounts of iron, so it possesses a low level of magnetic reaction. Since the area where the body is buried has proportionally less soil (the corpse takes up space), it will exhibit a lower level of magnetic reactivity. The magnetometer is passed above the soil and locates any areas that have low magnetic reactivity. 

Body Encased in Concrete: https://www.breitbart.com/crime/2019/10/17/police-find-missing-womans-body-encased-concrete-arrest-two-suspects/

Body in Concrete in Plastic Storage Container: http://usnews.nbcnews.com/_news/2012/10/13/14409189-murder-victim-found-entombed-in-concrete-was-former-fla-journalist

Acid in Tub: https://www.independent.co.uk/news/world/europe/french-students-dissolve-body-in-acid-after-killing-girl-in-breaking-bad-murder-plot-10447943.html

Body Beneath Another Corpse: https://www.newser.com/story/240700/husband-hid-wifes-body-under-grave-of-wwii-veteran.html

Body Parts in Trash Bags: https://6abc.com/archive/6880388/

Cooked Spouse: https://latimesblogs.latimes.com/lanow/2012/09/la-chef-told-police-he-slow-cooked-his-wife-for-days.html

Laci Petersen in the San Francisco Bay: https://en.wikipedia.org/wiki/Scott_Peterson

Corpse in Freezer in Truck: https://www.latimes.com/archives/la-xpm-1994-07-18-mn-17076-story.html

And

https://murderpedia.org/male.F/f/famalaro-john.htm

The Science of Finding Buried Bodies: http://theconversation.com/the-science-of-finding-buried-bodies-77803

The Science of Finding Dead Bodies: https://www.dailymail.co.uk/sciencetech/article-4515430/Researchers-reveal-track-corpse.html

 

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

 

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. 

1903: Will and William West Case–effectively ended the Bertillion System in favor of fingerprints for identification

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

 

 
 
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