Sometimes individuals get confused as to why investigators go in one direction or another at the beginning of an investigation. Inductive reasoning is generally used in the beginning of an investigation because given the data at the scene we first check on the most probable hypothesis as to what happened and who may be the suspect. For example: data shows that most serial killers are Caucasian males. So if the police have multiple suspects in a serial killing, they may look at the male Caucasian suspects first. The important point in using inductive reasoning is that one must remember to clearly distinguish between what is a probability and what is a fact.
These are most commonly seen in suicide or torture cases. The tool is most often a sharp object like a knife. They are superficial cuts to the skin, never intending to cause death but rather pain. Where the hesitation marks are can tell you much about whether they were self-inflicted or done for torture or control.
Knife Wound Analysis:
A good medical legal investigator has to know not only the anatomy of the body but also the anatomy of a knife. Most knives have a sharp edge and then on the opposite side a flat, non cutting edge called a spine. This is a single edged knife. Some knives are actually “daggers” and have sharp edges on both sides. Some knives have a “quillion” or “hilt” just before the handle of the knife. Each part of a knife’s anatomy can tell us the angle of attack, the length of the blade, the design of the blade or the shape of the hilt. Having a working knowledge of knives and understanding pattern wounds on the body can tell you much about the knife and the perpetrator.
A badly burned body is typically found in this position which is characterized by bent elbows, knees, hip and neck, with the hands clutched into a fist. This is because the fire affects the tissues and muscles in certain ways, shortening and stiffening them. The body has many different tissues, each with a different structure and density. Tendons, muscles, skin, bone are destroyed by fire at different rates. Because of this phenomenon a body that has been in a fire leaves certain artifacts. One of the first tasks of a medical legal investigator is to distinguish between peri-mortem trauma and fire-related artifacts.
In a fire death may times the epidermis of the fingers separates from the inner layers of the skin. The fire causes this condition but in some cases does not incinerate the hand because of position or some other reason. A pathologist or investigator can excise this outer layer of skin and place it on their own gloved finger of thumb and get very good thumb or fingerprints. This process is also often used in drowning case for identification purposes.
A commercial cremation chamber is similar to a large pizza oven. The walls of the oven are brick-lined and the chamber can be heated up to approximately 1800-2000 degrees Fahrenheit. Because of EPA requirements there is a second lower chamber that incinerates the smoke from the first chamber. This process makes the smoke coming out of the chamber much cleaner. It can take several hours for the process and the cooling of the remaining ashes. Then remaining bone and ash is then sent through a “cremulator” which crushes any larger ash into a fine powder. In Pennsylvania and other states cremation permission must be given by the Coroner or the Medical Examiner for this process to take place. This is because there is little evidence left from commercially cremated remains.
Incident Command System:
In this age of terrorism and mass casualties there is more and more usage of a system to organize large crime scenes and mass disasters. It is called the “Incident Command System.” Large scenes require communication and cooperation between multiple organizations and government authorities. There has to be a central command that can serve as the hub for the purpose of safety, information and liaison. The command center also coordinates operations, planning and finances. If you think this sounds like setting up a corporation for one incident you are correct. Attached is a website with a good overview of the Incident Command System: https://www.osha.gov/SLTC/etools/ics/what_is_ics.html
Physical Anthropology: There are 206 bones in the human body. The study of these bones and what they can tell us about an individual is the study of forensic physical anthropology. It is a field that fascinates me and is one I have to be familiar with because of the many times I have to do shallow grave recovery. I am not an expert in every field but I must have a working understanding of each to know when and how they should be utilized in medical legal death investigation. Bones can give us an abundance of information such as:
The field of physical anthropology goes well beyond these forensic applications into the study of man’s ancestral history and the progression of other hominin ancestors. In most cases, forensics draws an anthropologist from academia or museum staff. This is because most coroner/medical examiner systems do not have enough cases to justify a full time anthropologist. This is an important fact if you are thinking of this field of forensics.
This is the study of the unique characteristics in the structure and development of an individual’s teeth. The vast majority of forensic identification is done by the study of peri-mortem dental records with post-mortem studies. Obviously the most useful part of dental records is dental x-rays but written dental records also contain valuable information that can lead to identification of a person. The formation and wear of our teeth is totally unique. We generally have 32 teeth and four sides to each tooth, so that is 128 aspects of individuality that can be compared. There are also multiple interventions of dental care such as amalgams, tooth extractions and appliances that can also be compared. There are multiple reasons for dental identification beyond criminal identification. Here is a good website to get more information: http://www.dentalcare.com/en-US/dental-education/continuing-education/ce401/ce401.aspx?ModuleName=coursecontent&PartID=2&SectionID=-1
During the investigation, I discovered a plant growing through the eye socket of of a skull. It was a macabre picture, but to me it was evidence that could give me a timeline as to when the person had been killed and buried. Many items can give you timelines: hair growth, half-life of medicines, mail on a doorstep, degradation of clothing. The plant I examined at the scene had to be collected, classified, studied and the growth rate duplicated. I needed a growth rate with a timeline estimation done by experimentation with the same species of plant. There are forensic botanists who can provide estimations of how long ago the body was buried. Botanists can also look at what is called vegetation of opportunity, which can help locate clandestine graves. This is a differentiation in vegetation from the surrounding area caused by the disturbance of the earth in the process of digging the grave.
I am often asked if a person was alive during the fire. It is a fairly simple question to answer in most cases, using deductive reasoning, which goes something like this: A human is a mammal. Mammals need to breathe to live. Humans breathe through the nose and mouth down into the bronchi of the lungs. Fires produce particulates in the air. When one breathes the particulates, there is sooting around the nose and mouth into the lungs. Therefore I can say yes the individual was alive during the fire, if that sooting is present. This is a process of top down thinking. It is based on a premise known to be true, leading towards a conclusion that must also be true. If you read the premise above, it can lead to only the one conclusion.
There is a certain amount of carbon monoxide in the atmosphere, somewhere between 0.05 to 5 parts per million. In our blood systems there is a cell whose purpose is to carry oxygen throughout the body. This cell is called hemoglobin or the red blood cell. Carbon monoxide has a better than 200 times greater affinity than oxygen to latch on to a red blood cell thus depriving the body of oxygen. This combination of carboxyhemoglobin is the percentage measurement of how many red blood cells have been replaced with carbon, depriving oxygen to the cells in the brain and throughout the body. Normal levels of carboxyhemoglobin are between five and for heavy smokers up to twelve percent. There are many factors that would indicate how quickly a person would be affected and die when over these limits. Carboxyhemoglobin is a necessary piece of evidence in any fire death.
The Merriam-Webster Dictionary defines it as “a substance used to accelerate a process (as in the spreading of fire).” The most common accelerants appreciated in fire investigations are volatile organic compounds such a gasoline, kerosene, lighter fluid or other combustible liquids. One might ask, how does one know that accelerants were used? In many cases investigators use a dog specially trained to detect multiple types of accelerants. Fire investigators study fire first by looking at patterns. They are trained to find the origin of the fire, calculate the heat of the fire and determine how it spread. They also collect samples at the point of origin and test for accelerants.