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Category Archives: General Forensics

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

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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

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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

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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?

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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.

 

Criminal Mischief: Episode #03: Time of Death

Criminal Mischief: Episode #03: Time of Death Notes

LISTEN TO THE PODCAST: https://soundcloud.com/authorsontheair/03-timeofdeath

The ME’s 3 most important determinations: Cause, Manner, and Time of Death

Part II: Time of Death Notes

DETERMINATION OF THE TIME OF DEATH 

Determining TOD is critical
Both an art and a science
The sooner after death the more accurate the estimate
Changes death variable and unpredictable. 

Physiologic TOD, Estimated TOD, Legal TOD

Always a best guess
None of the methods are very accurate

Body temperature
Rigor mortis
Livor mortis (lividity)
Degree of putrefaction
Stomach contents
Insect activity
Scene markers 

BODY TEMPERATURE 

Normal body temperature is 98.6F
Body loses or gains heat until it equilibrates with that of the surrounding medium.
The formula is: Hours since death = 98.6 – corpse core temperature / 1.5
Cold/wind/water increase heat loss
Obesity, heavy clothing, warm still air, exposure to direct sunlight, and an enclosed environment slow heat loss. 

RIGOR MORTIS 

Spasm due to chemical reactions within the muscle cells after death.
Loss of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) causes the muscles to contract and stiffen.
Later loss of rigidity from the putrefaction process.
Rigor begins throughout the body at the same time
Appears first in smaller muscles- face, neck, and hands
Relaxes in same pattern
General rule for rigor mortis is 12-12-12
Changes due to: activity, body temp, ambient temp,
Cadaveric spasm 

LIVOR MORTIS (Lividity)

Purplish—exceptions for CO (carboxyhemoglobin), Cyanide (cyanohemoglobin), Freezing
Dependent areas—lying, sitting, hanging
Pale support areas
Gravity, then leaking into tissues
Shifting vs Fixed—Onset 1/2 to 2 hours/fixed by 8 hours
Mismatch of pattern and body position

THE RATE OF BODY DECAY 

Time Since Death
Putrefaction—ambient temp/humidity
Internal bacteria—sepsis hastens
Water X2/BurialX4
Ultimately skeletonize
Floaters
Mummification
Adipocere-from chemical process called saponification-reaction between certain bacteria and the body’s adipose (fatty) tissues.

Stomach Contents:

Stomach empties in 2-3 hours—protein, fatty meals
Intestine transient @ 24 hours

Insect Activity

Forensic entomologist

Insects help in two basic ways: Predictable developmental stages (blowfly); succession of insect species
Changed by body location, weather, season, night

Scene Markers

Includes information at the scene or from witnesses or family and friends.
Missed appointments, uncollected mail or newspapers, and dated sales receipts
Victim’s clothing—dressed for work, or morning jog

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Criminal Mischief #02: Cause and Manner of Death Notes

Criminal Mischief #02: The ME’s 3 most important determinations: Cause, Manner, and Time of Death

Part I: Cause and Manner of Death Notes

CAUSE/MECHANISM OF DEATH:

Cause of death is why the individual died
Heart attack, GSW, traumatic brain injury, diseases

Mechanism-physiological derangement that causes death

One cause—several mechanisms

Example: MI-arrhythmia, cardiogenic shock, rupture 

Example: GSW—heart or brain damage, exsanguination. wound infection

One mechanism—several causes

Example: Exsanguination—GSW, ulcer, meds, disease 

Just as a cause of death can lead to many different mechanisms of death, any cause of death can have several different manners of death. A gunshot wound to the head can’t be a natural death, but it could be deemed homicidal, suicidal, or accidental.

MANNERS OF DEATH: For what purpose and by whose hand

NATURAL: Natural deaths are due to the workings of Mother Nature in that the death results from a natural disease process. Heart attacks, cancers, pneumonia, and strokes are common natural causes of death. This is by far the largest category of death that the ME sees. 

ACCIDENTAL: Accidental deaths result from an unplanned and unforeseeable sequence of events. Falls, automobile accidents, and in-home electrocutions are examples of accidental deaths. 

SUICIDAL: Suicides are deaths that come by the person’s own hand. Intentional self-inflicted gunshots, drug overdoses, or self-hangings are suicidal deaths. 

HOMICIDAL: Homicides are deaths that occur by the hand of another. Note that a homicide is not necessarily a murder. Homicide is a determination of the ME; murder is a legal charge that is determined by the courts. Though each would be ruled a homicide by the ME, the legal jeopardy is much different for a court verdict of negligent homicide as opposed to first- or second-degree murder. 

UNDETERMINED OR UNCLASSIFIED: This extra category is used in situations where the coroner can’t accurately determine the appropriate category. 

Examples:
Car/pedestrian
Heroin/Drug OD
GSW

Psychological Autopsy

Manner determines whether there is an investigation

Manner not fixed—can change
Proximate cause— the cascade of events

To Learn more about this subject grab a copy of
FORENSICS FOR DUMMIES

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Coffin Birth: An Ancient Egyptian Mystery and the Solving of a Famous Case

Coffin Birth is a term used to describe the delivery of a baby postmortem. That is, the mother is dead and sometime later the child is expelled from the uterus. How does this happen?

During human decomposition, which begins almost immediately at death, the bacterial destruction of tissues leads to the formation of gas within the tissues as well as within the abdominal cavity. Most of the bacteria of decay reside within the G.I. tract so abdominal gas accumulation would be expected. As this accumulation progresses, the intra-abdominal pressure rises. If the victim is a pregnant woman, this pressure can collapse the uterus and force the fetus through the cervix, the vaginal canal, and out into the world. This is called a coffin birth. This can occur days or even weeks/months after death. The timing mostly depends on the speed of the decay process, which in turn depends on the ambient temperature.

Italian researchers have recently found a medieval grave that suggests exactly that. From the arrangement of the maternal bones and those of the near-term child, it appears a coffin birth may indeed have occurred.

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Remember the famous Scott and Laci Peterson case? This is what happened to Laci and her unborn son.

Laci Peterson

Laci Peterson

Once the eight-month pregnant Laci was dumped into the San Francisco Bay, the decay process began. The coldness of the water caused a slowing of the decomposition so it took several months before enough gas accumulated to cause two important events that ultimately led to solving the case. First, her corpse became buoyant and floated to the surface and washed ashore, where it was found. The second is that a coffin birth occurred and her unborn child, Connor, was delivered and also washed ashore nearby. The location was near where Scott had said he had gone fishing on that Christmas Eve day. Locating the bodies placed him squarely at the disposal site. Gruesome and sad. Fortunately, Scott now resides in San Quentin.

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The Recovery of Laci and Conner

 
 
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