Primary Crime Scene:
When first arriving at the scene, the investigator must first determine if the body is at the primary scene or a secondary scene. This can be done through the examination of physical evidence, enabling investigators to determine if the patterns seen are consistent with the actual crime taking place at that very location.
For example, if wounds on the body are traumas consistent with copious blood flow but the body has no pooling around it, the body may have been taken to a secondary spot after the initial assault.
Patterns can reveal if the deceased was murdered in one location and transported to another in order to delay or prevent discovery; this then is considered a secondary scene.
High Velocity Blood Pattern:
High velocity blood spatter is typically attributed to gunshot patterns. There are many types of blood patterns and they can be given a qualitative value but not always because of one quantitative indicator such as droplet size. Blood pattern analysis largely relies on human judgement, which is somewhat subjective. It is based on looking at multiple factors within a crime scene and blood pattern analysis is a helpful interpretive tool.
High velocity blood patterns from gunshot wounds have the lowest error rate as compared to medium or low velocity patterns. This is because these patterns have a predominance of blood spatter where the droplets are 1 millimeter in diameter, which is like a misting of blood droplets and easily identifiable. Details like this are critical to crime scene reconstruction.
Patterns are never looked at separately—the analysis must include a whole view of the scene such as position of the body, position of the gun, direction of the spatter and surface where the blood landed. Additionally, any good death investigator always challenges their own hypothesis, even when the evidence appears obvious.
To one extent or the other, every autopsy involves the dissection of the human body. There are various methods of dissection but the most common one in forensic medical/legal investigation is the Virchow method, named for Rudolf Virchow. Born in Germany in 1821, Virchow is known as the founder of modern pathology due to inventing a systematic method of autopsy in which the process starts from the outside in. Each organ is dissected separately and fully examined. For example, once the chest plate is removed then the organs are observed in their position. In general, the heart is the first organ removed and examined, next the lungs are removed, and then the process continues, descending into the lower regions of the body. Once all organs are removed and examined the scalp is reflected backwards, the skull cap is sawed open and the brain is then examined.
During a forensic autopsy, there are numerous collections of samples and certain areas such as structures around the neck are closely examined. A forensic autopsy also involves toxicology and tissue slides. The entire process is documented with photos and a dictated autopsy report from the forensic pathologist.
Forensics means science applied to law. Entomology is the study of bugs. A forensic entomologist is someone who studies insects and a variety of anthropoids. In forensics, this science is connected with the study of decomposition of the human body. Insects are part of the process of decomposition especially the common house fly and their eggs, which become maggots that feed off the decomposing tissue. The study of what is called anthropophagi or the process of bugs eating humans is a complex study that can provide a timeline of where and when a person died. Forensic entomology can play a very important role in crime scene investigation and requires knowledge of the different types and phases of anthropophagic action.
A petechial hemorrhage is a very small dotted hemorrhage caused slight bleeding in the subcutaneous tissues. In medical legal investigation, they often appear in the face and eyelid area in mechanical strangulation cases. They are an artifact of the deprivation of oxygen to tissue. This can be caused by quick suffocation, strangulation and even some natural events. Like all other hallmarks of a particular action, petechial hemorrhage should be corroborated by other markings on the body or findings at the scene.
In every science, there is a language that one must learn. In math that language might be quadratic equations, in medicine and medical legal death investigation there are specific and universal terms used for different types of trauma. It is important for an investigator or a medical professional to use the most accurate words to describe wounds and know the appropriate terminology. Describing a wound properly is critical to the accuracy of a coroner’s report which can be then used as evidence.
A laceration is different that an incise mark, which is what most people call a cut from a sharp object. A cut occurs from the sharpness of the object such as a knife or a shard of glass. A laceration comes from an object coming in contact with the skin with dramatic force.
A laceration has distinctive differences from an incise or a cut. A laceration has roughness around the edges of the wound usually with some bruising. A laceration is a tear caused by force. The laceration will also have bridging of material like collagen or fat cells across the wound. Cuts have smooth edges and no bruising or bridging.
One of my favorite experts is Dr. Vincent DiMaio. His testimony of gunshot wound analysis is a great example of how forensic professionals describe wounds.
Trace Evidence Somatotactics:
This describes trace evidence in relationship to the relative distance from the central core of the body. It’s a more subtle analysis of trace evidence and critical for medical legal investigators in using the body as the center of analysis, before gradually working out to the perimeter of the larger scene.
If you think of the body like the drawing by Leonardo da Vinci’s man in a circle:
The chest or trunk of the body is called the “internal” area. Moving a bit off the trunk is what is called the “proximal” and this describes all the evidence right next to the trunk area. Next are the areas within the reach of the arms and legs, which is the “axial” area. The area just out of reach of the arms and legs is called the “distal” area of the search pattern. Finally, the area out of ordinary sensory contact of the body is called the “limbic” area.
In the most general sense, macroscopic analysis involves the analysis of the bigger picture, or large units or elements. It is able to be seen by the naked eye. In medical legal death investigation, it means looking at the whole, or the larger aspect of what is being investigated and how things relate to each other.
Microscopic analysis is looking at minute pieces of evidence many times through enhancements such as alternative light or magnification. It is not visible to the naked eye. In medical legal death investigation, it means analyzing invisible or indistinguishable trace evidence that can provide important information, ultimately playing into the overall macroscopic analysis of a scene.
Trace evidence is so small that magnification or enhancements such as alternative light spectrums or chemical treatment is needed to detect it. Clothing or carpet fibers, hair, or tiny fragments of stone, metal, glass or paint, are inevitably transferred in an exchange during a crime or a physical assault. Any action or movement in an area takes something and leaves something behind, as per Dr. Edmond Locard’s “exchange principle”- which became a standardized part of crime scene investigation in the late 1800s.
Potential & Kinetic Energy:
It is important to calculate the amount of energy needed to cause specific wounds on a body. This requires an understanding of potential and kinetic energies, having to do with the laws of thermodynamics. Potential energy has to do with the position of one object to another. Suppose you pull a rubber band back in order to strike your sister on the arm. You have created the possibility of energy once you let go of the rubber band. Kinetic energy is proportional to the velocity and mass of an object when it impacts on another. The energy is measured in Joules. This happens when the rubber band is let go and it impacts from a certain distance on your sister’s arm. Scientifically, the sound you hear from your sister is the result of her pain and frustration with you :)
It doesn’t happen often, but sometimes death scenes are staged. This occurs when the perpetrator wants you to believe a certain thing happened at the scene. They rearrange the evidence to lead suspicion away from themselves or even try to change the actual manner in which the person died. It could be hanging a person after they have been killed to make it look like a suicide or fake an illegal entry into a home to make one believe that an intruder caused the death, rather than someone from inside the home. The key to not being deceived by a staged scene is good scene documentation. The most valuable tool in documentation is photography. Overall, medium range and close up photographs preserve a scene in time. Even years later clues to staging can be found from the good work of the original CSI team. Detecting staging is the process of studying patterns. Many times those that stage try too hard and the look of randomizing events give way to overt patterns that one can tell are trying to lead the investigators to one conclusion. Staging a scene indicates a certain amount of premeditation and planning. This is important in building the profile of the suspect.
Just like the name implies, marks made by weapons or tools can tell us a lot. One example is a patterned wound on a body. A convex tool or weapon, like a tire iron or round rod will many times leave two parallel red lines on the body. This is because when the tool hits the body, the blood in the skin is pushed out to the side of the tool at impact. The center of the impact is blanched due to the loss of the blood in the area of impact. Tool marks on doors, furniture and other objects can lead to a particular classification of tool or may under a comparative microscope individualize the exact tool used by wear marks.
The general definition of the term is the study of the process of fossilization and body decay. I have spent multiple weeks down in Knoxville, Tennessee at the University of Tennessee “Body Farm,” a project started by a Dr. William M. Bass in conjunction with several cooperating medical examiners offices. The purpose of the farm is to examine the process of human body decomposition from a forensic investigative point of view. Today there are six such facilities in the United States and they have given forensic investigators, physical anthropologist and medical legal investigators invaluable information concerning the various hallmarks of decomposition including time lines, methods of documentation and the process of recovery for evidentiary purposes. Taphonomy is now one of the major fields of study in death investigation and human identification.
I know this may seem gross but it is necessary to understand artifacts that are postmortem and those that are perimortem. Postmortem refers to that which occurs after death and perimortem refers to that which occurs at or near the time of death. Many new to the field of death investigation will see liquid coming out of the mouth and nose of a decomposing body, and mistake it for perimortem trauma. However, the liquid is the result of a breakdown of tissue, being pushed out of the opening of the body due to the buildup of gasses. Close examination at the lab is the best way to categorize true trauma to the body.
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.
Behavior Evidence Profiling:
Evidence is first recognized, documented, collected and then processed, usually by identification teams, made up of crime scene investigators. The next step, usually done by detectives, is investigative work, which compiles all the evidence and asks the question “why.” Why is the body in that position? Why are the casings in the other room? Why was there no forced entry? This is the reconstruction phase of the process. It is not enough to have the evidence. The meaning must be decoded. It is in the reconstruction process where the final picture develops and the scene and the body start to tell their story.
Patterns are important on all phases of the investigation but a medical legal investigator is mainly concerned with those wounds on or about the body. Sometimes the absence of certain types of wounds tell you as much as their presence. In the Ewalt case it was the absence of defense wounds and the lethalness of her two wounds that told me this was most likely an experienced killer. Her wound patterns were not consistent with most domestic or passion killings. The pattern wounds on the victim’s body many times tell the intent and purpose of the killer.
My work at the scene starts at the body and works outward towards the edges of the infamous yellow tape. I first look at body position because it is the beginning of the body speaking to me. Has it been moved? Was there a struggle? Was the death quick or agonizing? In Darlene’s case it was clear that the attack was sudden, from behind, and death was almost instantaneous.
Blood Pattern Analysis:
Blood has specific properties—one of those is surface tension. Because of this feature of blood, it can be analyzed mathematically as to origin and angle of impact. There are numerous types of patterns: transfer, low, medium and high velocity patterns, pooling patterns and arterial spurt patterns. The patterns at a scene and on the body can give information of movement at the scene, sequencing of the wounds, and how many persons were at the scene. Because of the importance of blood patterns, scene security and processing must be treated meticulously.