Forensic Friday: Forensics during the 1940s

Forensic Friday: Forensics during the 1940s

Although in some ways, forensic science was in its infancy during the 1940s, police officers and detectives took evidence collection seriously, recognizing that physical clues were a crucial part of any investigation. These 1940s photos show how much things have changed since then:

Crime lab employee James Haas compares an imprint of tire marks found near a murder victim with those of the car belonging to the suspect.





Police getting rid of "hooch," better known as moonshine. It looks to me as if it is being flushed down the town's water system. I don't think that's how it's done nowadays.

There was no indication of what they fellas were looking for, but it seems to me they might be contaminating a crime scene by standing in the middle of whatever that is on the ground!





An American soldier was convicted and hanged for the murder of three women in Melbourne, Australia. With any luck the barrier the police officers are standing behind kept too many folks from marching through the crime scene.

Forensic Friday: Toxicology

Toxicology: The Real Story

By definition, toxicology is a branch of biology, chemistry, and medicine that studies the adverse effects of chemicals on living organisms. A toxicologist analyzes biological fluids and tissues from victims who are thought to have been poisoned accidentally or purposely. Different from a forensic chemist, the toxicologist primarily handles biological materials and can detect poisons in blood, urine, spinal fluid, gastric contents, bile, and tissues. Forensic toxicology is the use of toxicology and other disciplines in a legal or medical investigation of death, poisoning, or drug use.

Marie LaFarge

The various crime dramas on television shows would have us believe toxicology is a new science, made possible only by modern technology. However, there are ancient records that prove otherwise. A doctor, pharmacologist, and botanist, Dioscorides lived from 40-90AD (during the reign of Nero – a crazy man, but that’s for another post!) A medic in the Roman Army, he is thought to have made the first attempt to classify plants by their toxic and therapeutic effects. The Book of Poisons was written by Ibn Wahshiyya around 900 AD. Considered the father of modern toxicology, Mathieu Orfila was used as an expert witness in the trial of Marie LaFarge, who was accused of poisoning her husband in 1840.

 

The goal of the toxicologist is to identify and quantify the presence of drugs and chemicals in blood and tissue samples. The challenge to the process is that a chemical rarely remains in its original form once ingested into the body. For example, heroin is metabolized into morphine. A toxin also may become diluted as it passed through the body.

Toxicologists have their work cut out for them. With the media looking over their shoulder, and law enforcement officers anxiously awaiting results, I would imagine the temptation would be to rush tests and hurry through analysis. However, accuracy, validity, and reliability are the legs upon which reputation of a skill toxicologist is built.

Forensic Friday: Bugs!

Forensic Friday: Bugs!

I don’t mind snakes, but I hate bugs. How about you?

However, insects can play an important part in crime solving. The field of forensic entomology goes back almost a millennium. In 13^th century China a book titled “The Washing Away of Wrongs” describes the first known recorded incident where insects were used in a criminal investigation. A farmer was found murdered in a field of an apparent stabbing. The suspects were told to place their sickles on the ground. Only one sickle attracted blow flies to the trace amounts of blood hidden to the naked eye. This led to the confession by the murderer.

Advancements continued. In 166, Italian physician Francesco Redi disproved the theory of spontaneous generation. French physician Louise Francois Etienne Bergeret published a report in 1855 about the life cycle of insects that he used to prove his hypothesis on how and when the victim died.

How does medicolegal forensic entomology work?

·         Technicians collect insect evidence from the corpse and the crime scene. Depending on which insects’ eggs appear, and where they are located on the body, the medical examiner can determine the approximate time of death (also known as post mortem interval or PMI).

·         Because many insects occur only in certain places or are active only in certain seasons or time of day, potential links can be made to times and locations where other events may have occurred. This information can also indicate if a body has been moved.

·         Medical examiners must keep in mind that rain, humidity levels, sun exposure, and air exposure can impact the presence (or not) of insects.

Photo courtesy of www.purdue.edu

A new subfield is entomotoxicology – the analysis of toxins in the insects found on the corpse – helps investigators determine whether drugs were present in a body at the time of death. In addition, new techniques have been developed to more accurately gather evidence at crime scenes.

Who knew bugs could be so important?

Forensic Friday: Botany

As noted in previous blog posts, forensics has numerous specialty areas. One of those specialties is botany. Forensic botany is the application of plant sciences to criminal investigations. Similar to DNA and fingerprinting, plant material (seeds, leaves, flowers, spores, wood, fruits, cells, hairs and glandular hairs) is often unique to certain plant species and ecological areas. This allows a forensic botanist to narrow down the possibilities surrounding the who, where, and when of a crime.

An example of this is the comparison of pollen at a crime scene and on a suspect. Because even common plants have their own unique combination of pollens at different locations, the botanist may be able to link the suspect to a particular crime scene or determine that the victim has been moved from the original crime scene. Another example is the use of botanical evidence to find “clandestine” graves by examining the changes of disturbed soil. Botanists are knowledgeable about the plants that typically invade disturbed surfaces.

The study of trees and roots is also helpful in an investigation, often for determining the elapsed time of death. Growth rings can be counted to provide the timing of an event, and even partial damage to root growth can suggest the period since an interruption occurred.

The first reported trial that used the expert testimony of a botanist was the Lindbergh baby kidnapping case. Dr. Arthur Koehler was an expert on wood anatomy and identification with the United States Forest Service. He studied the ladder used by the kidnapper, and subsequently presented three kinds of information – identification of the wood used, physical marks left by tools on the wood, and comparison of the wood structure. By matching the annual rings on the wood, Koehler was able to show that the attic board in Bruno Hauptman’s home and the ladder rail had once been a single board. This was one of the most incriminating pieces of evidence in the trial that led to Hauptmann’s conviction.

In the eighty years since the Lindberg trial, the value of botanical trace evidence in criminal and civil cases has been used to bring justice to innumerable victims.

Forensic Friday: Pattern Evidence

Tire track impressions leave behind a unique pattern, therefore are classified as pattern evidence. Just like shoe impressions can help narrow down the brand, style and size, tire tracks have the ability to do the same thing. The type of evidence left behind depends upon the type of surface traveled. A tire can leave an impression in loose sand or snow, but will leave an imprint on a hard surface such as concrete.

There are three types of prints: visible – able to be seen by the naked eye and collected by photography; plastic – three-dimensional and collected by making a cast; and latent – prints not visible to the naked eye. In modern times, latent prints are collected through the use of electrostatic lifter dust.

Once impressions or imprints are collected at the crime scene, experts compare the evidence to a suspect’s shoe or vehicle tire to determine if the item is the same one that left the impression. The reason this works is that as shoes and tires are used, their physical features change over time. For example, a tire out of alignment will create a tire that is heavily worn along one edge.

An example of the use of tire impressions as evidence is in the recent case of former Patriots tight end Aaron Hernandez. Four stones wedged in the tread of the rear passenger-side tire on a vehicle rented to Hernandez enabled investigators match it to the tire tracks left at the scene of the crime. A miniscule yet crucial piece of evidence.

Forensic Friday: Every Contact Leaves a Trace

photo: dfs.Virginia.gov

In my early college days, I aspired to be a medical technologist. Dr. Pinkerton’s Organic Chemistry class, and the thought of spending hours on end squinting into the eye piece of a microscope sent me running across campus to the Psychology department where I happily stayed until I received my bachelor’s degree in Psychology.

Having said that, I find the forensics aspect of crime solving absolutely fascinating. So much so, that I follow forensic anthropologist Dr. Elizabeth Murray on Facebook and own her two Great Courses on forensics. Not to mention several forensic textbooks. After reading them I no longer look at my hair and clothes the same way.

During the investigation of a crime, hair and fiber are collected at varying points throughout the process, but most notably at the scene of the crime and at the autopsy stage. This can be for the purposes of eliminating individuals from police enquiries as well as to help narrow down the list of suspects. These samples are collected through meticulous and painstaking processes, which are carried out by Crime Scene Investigators who themselves are dressed in protective clothing so that their own clothing and hair do not contaminate any evidence which may pre-exist.

The fibers are then taken back to a lab to be analyzed. It is a time consuming job, and doesn’t happen as quickly as shown on television, but has been crucial in solving many high profile cases including the Lindbergh kidnapping in 1936. Science has come a long way since then, but sometimes it is still the simple details of a single fiber that clinches a conviction.