RSS

Category Archives: crime lab

Holmes, Thorndyke, Locard, Gross, and the Modern CSI

There are no bigger names in the history and development of modern crime scene investigation than French investigator Edmond Locard and his Austrian counterpart Hans Gross. These two men shaped the development of crime scene investigation and even today their techniques create the cornerstone of forensic science. Locard’s Exchange Principle underlies every forensic technique.

locard1

EDMOND LOCARD

hans-gross

HANS GROSS

They were also great fans of Sir Arthur Conan Doyle’s Sherlock Holmes and R. Austin Freeman’s Dr. John Evelyn Thorndyke. Locard even suggested that students of police procedure read the Sherlock Holmes stories and learn from his techniques.

Sherlock_holmes_paget_slider

Both the real-life investigators and the fictional ones had one thing in common: the careful and meticulous approach to any crime scene, taking care to collect all useful evidence, while not damaging or contaminating it.

In my book Forensics For Dummies, the methods and techniques used to evaluate a crime scene and collect evidence are explained in great detail. Check it out if you want to know more about the techniques that saw their origin more than 100 years ago.

FFD 300X378

Advertisements
 

The Queen of Poisons and The Marsh Test

ii_b_114c

Arsenic has, over the centuries, garnered many colorful names. It was called the “queen of poisons” because it was so readily available, easy to use, highly effective, and untraceable. Thus, it was used by many famous historical poisoners. Some called it the “king of poisons” but since over the years,  female killers have favored poisons, “queen” seems more apt. It was also called “inheritance powder,” for obvious reasons—-once the estate holder is dead and gone, the heirs can party down.

Arsenic is the nearly perfect poison. This was definitely true centuries ago when there was no way to trace it. But what about today, with modern toxicological techniques? Unfortunately, arsenic is still a pretty good choice for the poisoner. It’s not often looked for in unexplained deaths and its effects mimic many medical conditions, particularly neurological and gastrointestinal.

Back a couple of centuries ago, because of its common use, a method for finding arsenic in the dead or ill became an imperative. There were many steps along this path. This search for arsenic was essentially the beginning of forensic toxicology.

From HOWDUNNIT: FORENSICS

Arsenic had been a common poison for centuries, but there was no way to prove that arsenic was the culprit in a suspicious death. Scientists 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 char- coal, 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) devel- oped 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.

I ran across an excellent article on the Marsh Test and it’s definitely worth a read. I can imagine when this was performed in the courtroom it did elicit a few gasps.

A few useful links:

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

http://www.atlasobscura.com/articles/marsh-test-arsenic-poisoning

http://www.huffingtonpost.com/sandra-hempel-/arsenic-the-nearperfect-m_b_4398140.html

http://www.dartmouth.edu/~toxmetal/arsenic/history.html

 

Howdunnit Forensics Cover

 

How Old Is That Fingerprint?

Fingerprint

Fingerprints are useful forensic science tools. They’ve been so for over 100 years. Mainly, it’s the pattern of the ridges on the fingertips that supply the useful information. We know that everyone has different fingerprints and we know that they do not change throughout the person’s life. This means that they are highly reliable sources for identification and for discrimination between two individuals. Law enforcement has employed this for years.

But several newer techniques and analyses allow investigators to go even deeper. The skin cells, that are part of a fingerprint, can often yield DNA. Chemicals in the print residue can sometimes reveal if the person has used or handled such substances as cocaine. Other analyses are underway that might make fingerprints even more useful.

One question that frequently plagues crime scene investigators is exactly when a print was laid down. This determination can make a huge difference. Let’s say that a print is discovered at a homicide scene and the primary suspect says that he had been at that location but that that had taken place a week earlier. Not on the day of the killing. Is he telling the truth? Or simply trying to throw the police off and make an excuse for the evidence they collected against him? It would be nice to know if the print was 24 hours old or seven days old.

Research is currently underway by Shin Muramoto and his colleagues and they reported their initial findings in a recent article in Analytical Chemistry. They discovered that a chemical found in fingerprints known as palmitic acid migrates away from the ridges at a predictable and consistent rate. By looking at this migration pattern they are able to determine whether the print is fresh or up to four days old. They are looking to extend this envelope to a longer period of time. But you can see, that even this level of discrimination could help—or not—- the suspect in the above scenario.

 

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Check out the new posts John Raab of Suspense Magazine and I put together. Read the Q&As and listen to the expanded discussions. Hope each proves helpful for your crime fiction.

Can DNA Be Used To Identify Multiple Assailants In a Three Decade Old Rape?

http://suspensemagazine.com/blog2/2016/12/20/d-p-lyles-forensic-file-episode-1/

In 1863, Could An Autopsy Accurately Determine the Cause of Death?

http://suspensemagazine.com/blog2/2017/01/09/in-1863-could-an-autopsy-accurately-determine-the-cause-of-death-d-p-lyle-answers-this/

Can My Female Character Cause Her Pregnancy To Become “Stone Baby” By Shear Will?

http://suspensemagazine.com/blog2/2016/12/31/can-my-female-character-cause-her-pregnancy-to-become-stone-baby-by-sheer-will/

More to come.

Want more cool questions from crime writers? Check out my three Q&A books.

M&M 200X300

More Info and List of Included Questions

F&F200X302.jpg

More Info and List of Included Questions

MF&F 200X320

More Info and List of Included Questions

 

Crime and Science Radio: Crime Scenes, Criminalistics, and the Cutting Edge

Crime and Science Radio: Crime Scenes, Criminalistics, and the Cutting Edge in Los Angeles: An Interview with Former LASD Criminalist Professor Donald Johnson of California State University, Los Angeles

BIO: Professor Donald James Johnson is an expert on criminalistics, with emphasis on crime scene investigation and reconstruction (homicides and sexual assaults), and forensic biology. His research interests include the application of new technologies to the field of criminalistics. He was formerly a senior criminalist at the Los Angeles County Sheriff’s Department, where he was involved in the scientific investigation of violent crimes.

NOTE: This show was recorded live at the MWA-LA Chapter meeting in Los Angels, CA

LISTEN: LISTEN: http://www.blogtalkradio.com/suspensemagazine/2016/09/10/crime-and-science-radio-with-special-guest-dr-donald-james-johnson

Link will go live Saturday 9-10-16 at 10 a.m. Pacific

LINKS:

California Forensic Science Institute: http://www.calstatela.edu/hhs/cfsi

School of Criminal Justice and Criminalistics at CSULA: http://www.calstatela.edu/hhs/crim

CSULA Masters in Criminalistics http://ecatalog.calstatela.edu/preview_program.php?catoid=11&poid=3452

Los Angeles County Sheriff’s Department Scientific Services video: https://www.youtube.com/watch?v=SboLJ7WwnXQ

Los Angeles County Sheriff’s Department: http://sheriff.lacounty.gov

American Academy of Forensic Sciences http://www.aafs.org

 

Q&A: Will a Decaying Corpse Actually Produce Alcohol?

whiskey glasses

 

Q: Is it possible or likely for blood alcohol levels to increase or decrease in a decomposing body, and if so during what stages of decomposition?

A: Alcohol is usually consumed in the decay process but may actually be produced and this might cloud any toxicological examinations on the corpse. Make it look as if the victim consumed more alcohol than he actually did.

I must point out that alcohol is not commonly produced but it does happen in rare cases. The alcohol is a byproduct of the action of some types of bacteria that are involved in the decay process. This means that alcohol can only appear during active decay. What is that time period? A little about putrefaction.

The decomposition of the human body involves two distinct processes: autolysis and putrefaction. Autolysis is basically a process of self-digestion. After death, the enzymes within the body’s cells begin the chemical breakdown of the cells and tissues. As with most chemical reactions the process is hastened by heat and slowed by cold. Putrefaction is the bacterially mediated destruction of the body’s tissues. It is this decay that might cause some alcohol formation. Not always, but sometimes. The responsible bacteria mostly come for the intestinal tract of the deceased, though environmental bacteria and yeasts contribute in many situations. Bacteria thrive in warm, moist environments and become sluggish in colder climes. Freezing will stop their activities completely. A frozen body will not undergo putrefaction until it thaws.

Under normal temperate conditions, putrefaction follows a known sequence. During the first 24 hours, the abdomen takes on a greenish discoloration, which spreads to the neck, shoulders, and head. Bloating follows. This is due to the accumulation of gas, a byproduct of the action of bacteria, within the body’s cavities and skin. This swelling begins in the face where the features swell and the eyes and tongue protrude. The skin will then begin to “marble.” This is a web-like pattern of the blood vessels over the face, chest, abdomen, and extremities. This pattern is green-black in color and is due to the reaction of the blood’s hemoglobin with hydrogen sulfide. As gasses continue to accumulate, the abdomen swells and the skin begins to blister. Soon, skin and hair slippage occur and the fingernails begin to slough off. By this stage, the body has taken on a greenish-black color. The fluids of decomposition (purge fluid) will begin to drain from nose and mouth. This may look like bleeding from trauma, but is due to extensive breakdown of the body’s tissues.

The rate at which this process occurs is almost never “normal” because conditions surrounding the body are almost never “normal.” Both environmental and internal body conditions alter this process greatly. Obesity, excess clothing, a hot and humid environment, and the presence of sepsis may speed this process so that 24 hours appear like 5 or 6 days have passed. Sepsis is particularly destructive to the body. Not only would the body temperature be higher at death, but also the septic process would have spread bacteria throughout the body. In this case, the decay process would begin quickly and in a widespread fashion. A septic body that is dead for only a few hours may appear as if it has been dead for several days.

As opposed to the above situations, a thin, unclothed corpse lying on a cold surface with a cool breeze would follow a much slower decomposition process. Very cold climes may slow the process so much that even after several months, the body appears as if it has been dead only a day or two. Freezing will protect the body from putrefaction if the body is frozen before the process begins. Once putrefaction sets in, even freezing the body may not prevent its eventual decay. If frozen quickly enough, the body may be preserved for years.

So, whether a particular corpse actually produces alcohol or not is totally unpredictable. How long it takes depends upon the conditions the corpse is exposed to. In a corpse in an enclosed garage in Houston in August, this process will be very rapid and the corpse will be severely decayed after 48 hours. If parked in a snow bank in Minnesota in February it might not even begin the decay process until April or May when the spring thaw occurs. And anything in between. The appearance of any alcohol would coincide with the time frame of the bacterial activity.

So how does the ME get around this possibility? How can he determine the actual alcohol level that was present prior to the decay process kicking in? He can’t with any absolute accuracy, but he does have a tool that will help him make a best guess. He can extract the vitreous humor from the victim’s eye—this is the jelly-like fluid that fills the eyeballs. The alcohol level within this fluid matches that of the blood with about a two-hour delay. That is, the level within the vitreous at any given time reflects the blood alcohol level that was present approximately two hours earlier. And the vitreous is slow to decay so it might be intact even though the corpse is severely decayed. By measuring the vitreous level the ME will know the blood alcohol level two hours prior to death and he can then estimate the blood alcohol level at the time of death.

 

MF&F 300X481

This question originally appeared in MORE FORENSICS AND FICTION

http://www.dplylemd.com/book-details/more-forensics-and-fiction.html

 

Crime and Science Radio Goes Live at MWA-LA

CSR 300x250-72dpi

Mark your calendars for this event. Jan and I are recording an episode of Crime and Science Radio live with our special guest Criminalist and Forensic Science Professor Don Johnson. This will be a fun and informative event. Sign up now.

From MWA-LA

We have a special luncheon planned in August:

D.P. Lyle and Jan Burke Live Radio Podcast with special guest interviewee Criminalist and Forensics Professor Don Johnson

This will be a unique opportunity to experience a live podcast with three outstanding experts

Sunday, August 7, 2016

Tam O’Shanter Restaurant

2980 Los Feliz Blvd.

Los Angeles

Doors open at 11:30

MORE INFO:

http://www.socalmwa.com/2016/05/tam-luncheon-dp-lyle-jan-burke-live-radio-podcast/

 
 
%d bloggers like this: