Forensic Anthropology is the science of physical anthropology when applied to the legal process. Often times authorities are faced with badly decomposed corpses, unidentified remains, or merely skeletons. Using scientific techniques developed in anthropology, forensic anthropologists may work in conjunction with forensic odontologists, pathologists, and homicide investigators to determine the age, sex, stature and more from human remains. Prime examples of the application of this science is to identify victims of wartime massacres. A good example of its use in CSI is when Gil had the facial features of a deceased woman constructed from skeletal remains in the episode "Who Are You".
Forensic Art A good example of forensic art in CSI is when Grissom had the facial features of a deceased woman constructed from skeletal remains in the episode "Who Are You".
Forensic Entomology is the use of insects and other arthropods that are found at decomposing remains to aid criminal and civil investigations. This field can be divided into three general areas: medicolegal, urban, and stored product pests. Medicolegal focuses on criminal investigations and the carrion feeding insects found on human remains. (For instance, when Gil employed forensic entomology when he found the insect on the corpse in the Pilot episode of CSI. The urban aspect focuses on insects that affect man and his environment, and those insects can feed on both living and dead humans. More often than not, the urban aspect is involved in civil proceedings and not criminal investigations. The stored product aspect involves food contamination, in which the criminologist may serve as an expert witness in both criminal and civil proceedings.
Forensic-Entomology.com - Insects in Legal Investigation - An excellent site for this branch of forensic science. Highly recommended!
Forensic Medicine / Science
Forensic medicine is the application of the science of medical and paramedical specialties (i.e., dental, chemical, psychological, biological, and mechanical techniques) in determining the cause(s) of an individual's death, injury or disease. For example, forensics is applied from murder to child abuse.
Forensics.ca - General forensics site from Canada. Good selection of material. Court TV's Forensic Files - A companion website to the TV Series seen on the cable channel Forensic Files, seen in the USA.
Forensic Odontology is the application of the science of dentistry and paradental knowledge to help solve criminal and and civil matters.
Forensic Palynology
Forensic Palynology uses pollen and spores to help solve crimes. Many pollens and spores are specific to regions, even states, and can also help determine where items - such as food, merchandise, vehicles - have come from.
Forensic Photography is the utilization of photographic techniques to capture the crime scene in photographs. You just can't drag along your instamatic, y'know....
Forensic Psychology/Psychiatry is the application of the science of psychology/psychiatry with legal issues, which can cover trauma, serial killers, stalking, false memories, etc.
Ballistic - One of the most popular aspects of forensics, at least on TV shows: the study of guns and bullets in relation to crimes.
FirearmsID.com - Everything you wanted to know about this field.
Blood Spatter - When people are violently killed, their blood usually tends to spatter the environment (walls, floors, etc.). How that occurs can determine the angle of impact, the item used, etc. Also called blood spatter.
BSCO Blood spatter Page - Contains terminology page, chart of bloodstain patterns, and more.
Cleaning Up the Scene
Although the gang on CSI are basically first on the scene, viewing sometimes gruesome visages, that's it. Someone else does the clean-up. For the gory details (pun intended)
Crime Scene Investigation
A criminalist is a specialist who collects and examines physical evidence found at the scene of a crime. For more information on what a CSI is, go to the FAQ page.
Crime-Scene Investigator.net - Bookmark it for fun: crime scene response, evidence collection, photography, articles, training and employment, resources and links.
Crimes and Clues: The Art and Science of Criminal Investigation - From fingerprints to pathology
Criminalist - A specialist in the collection and examination of the physical evidence of crime.
Criminalists Careers - site gives all the information on what a criminalist is, and the jobs he/she does
DNA - The most common technique known to the layman is DNA forensic analysis, in which scientists focus on certain genetic sequence called markers, which is particular to each person. DNA evidence, if preserved properly, can be used decades after the crime to incriminate - or clear - suspects.
DNA and Forensics - Good writing resourse that also tells how DNA works in the legal system
Evidence - Forensic science studies many facets of the crime scene: fingerprints, DNA, serology, firearms, drugs, and much more. Anything from a hair to a twig to a dead insect can yield important evidence to solve a case.
The FBI page on collection and storage of evidence: trace=hair, fingerprints, blood swabs and DNA; Documents=Printouts, forms, photographs, or receipts, etc; Items= materials gathered at the crime scene, such as weapons, clothing, and other larger pieces of evidence
Fingerprints - no two fingerprints are the same. They are uniquely individual. Finding all of, or portions of a fingerprint can, without doubt, connect the suspect to the crime scene
Firearms / Explosives
Most murders (at least on TV) are committed with firearms. Learn more about how forensics determines the distance, the type of weapon used, and more. Criminals and, more often, terrorists, are overly fond of explosives.
Arson & Explosives - Arson and Explosives are use to commit the crime as well as attempts to cover up the crime
Knots & Ligatures
Many people are strangled, and forensics experts can determine what is used by the evidence left behind. Forensic Knot Specialists/Experts do exist.
Forensic Knot Analysis - RCMP page on the use of ligatures and murders. Warning: contains disturbing graphics.
Questioned Documents NEW!
You've heard this department mentioned on CSI, in particular the episode "Gentle, Gentle." They handle basically anything that's written, whether by hand or machine.
Included on this page, you will find some information designed to help with your writing research on the subject of Crime Scene Investigation and Forensics.
Introduction to Blood Spatter Analysis
Background
An explosion in media coverage of real crimes, as well as fictitious crime scenes depicted in television dramas has fueled a vast increase in public interest in forensic science techniques. Popular television shows and detective novels often depict the forensic scientist as a sort of jack of all trades, solving crimes and capturing criminals. In reality, these activities fall under the job description of the detectives in charge of the crime. The work of forensic scientists is broken down into several highly specialized subsets. Crime labs have several departments, each having their own staff of highly trained specialists that help analyze and examine each piece of evidence that is collected at the crime scene. Full service crime labs have the capability to examine blood, DNA, firearms, tool marks, drugs, alcohol, handwriting, documents, photography, video footage from the crime scene, trace evidence, and more. Each of these involves specific techniques requiring a great deal of expertise. In addition, most labs also employ several crime scene specialists that are called to the actual scene of the crime. These specialists are trained to secure and closely examine the crime scene for evidence that may elude the police officers handling the scene. The following chart shows a small portion of the specialty areas required to investigate specific types of evidence:
There are hundreds of methods and analytical techniques used in the forensic laboratory. While many of these methods are common biological, immunological, biochemical, or microscopic tests used in scientific research, others are unique to the forensic field. Forensic analysis is not only concerned with recognizing and identifying unknown substances, it is also actively used in the complete reconstruction of crime scene events and conditions.
One technique used by crime scene investigators is the analysis of stains left by blood shed at a scene. Bloodstain pattern analysis is a powerful forensic tool used in crime scene investigations. If the investigator understands the dynamics of an altercation, how blood be haves when it exits the body, and how it reacts when it contacts a surface, then an attempt can be made to understand what happened and to determine if a crime occurred. The trained forensic scientist looks at the patterns made by shed blood and tries to determine what did and/or did not happen. Interpreting the bloodstain patterns involves physical measurement of blood droplets, pattern recognition using known photographs or experiments, the use of trigonometry, and knowledge of the physics of motion. Together with other types of evidence from the crime scene (such as fingerprints, tool mark and footprint impressions, DNA evidence, chemical analysis, etc.) the forensic investigator pieces together the puzzle to re-create a logical sequence of events, which is supported by crime scene evidence. Collecting and documenting the evidence correctly is another skill just as important as interpreting evidence. Bloodstains cannot always be carried back to the lab, so care in documenting the scene is of utmost importance. Photographs and detailed sketches drawn to scale are invaluable tools that help piece together the puzzle.
Glossary of Key Bloodstain Pattern Analysis Terms
Angle of Impact: the angle at which a blood droplet strikes a surface
Arterial Gushing: the large pattern of blood that is created when blood escapes an artery under pressure; the increase and decrease in blood pressure is apparent
Arterial Spurts: large patterns created under pressure, but with less volume and usually more distinctive evidence of blood pressure rising and falling
Clot: a mass of blood and other contaminants caused through clotting mechanisms
Cast-Off Stains: blood that has been thrown from a secondary object (weapon or hand) onto a target other than the impact site
Drop Patterns: characteristic patterns present when blood drips into standing, wet blood
Expiratory Blood: blood which is spattered onto a target, as a result of breathing; typically, this occurs when an injury is sustained to the throat, mouth, or airway
Impact Site: usually the point on the body that received the blow or applied force, from which the blood was shed
Origin: the point in space where the blood spatter came from
Parent Drop: the droplet from which satellite spatter originated
Projected Blood: blood under pressure that strikes a target
Satellite Spatters: small drops of blood that break off from the parent spatter when the parent droplet strikes a target surface
Shadowing/Ghosting/Void: a pattern that helps to place an object or body in the scene; normally, the area in question lacks blood even though areas surrounding it show blood
Skeletonized Stain: the pattern left when an object moves through a partially dried stain, removing part of the blood, but leaving the outline of the stain intact
Spatter: bloodstains created from the application of force or energy to the area where the blood is
Spines: the pointed edges of a stain that radiate out to form the spatter
Splash: pattern created when a volume of blood in excess of 1 mL strikes a surface at a low to medium velocity
Swipe: the transfer of blood onto a target surface by a bloody object that is usually moving laterally
Transfer Pattern: the pattern created when a wet, bloody object comes in contact with a target surface, leaving a pattern that has the features of the object making it useful for identifying the object
Target: the surface where the blood ends up
Wipe: pattern created when a secondary target moves through an existing wet blood stain on some other object
CRIME SCENE BLOOD STAIN ANALYSIS AND EVIDENCE COLLECTION OBJECTIVES
~Establish the relationship between dropping height and blood drop diameter
~Recognize patterns around the drop, such as satellite spatter or spines
~Develop an understanding of the common types of bloodstain patterns found at a crime scene
~Create and examine vertical blood drop patterns on various textured surfaces
~Differentiate between high velocity and medium velocity impact spatter .
THIS MONTH'S FEATURED SUBJECT
Type of Evidence Area of Specialty
Blood groups .................... Serologist
Body tissue ....................Pathologist
DNA/RNA .................... Molecular Biologist
X-rays .................... Radiologist
Dentition and dental work ..................... Odontologist
Insects ..................... Entomologist
Plants ..................... Botanist/phycologist
Soil ..................... Microbiologist
Algae and other microbes ..................... Geologist
Paint and glass fragments ..................... Chemist
Drugs and poisons ..................... Toxicologist
Properties of Blood
Blood Volume
On average, accounts for 8 % of total body weight
5 to 6 liters of blood for males
4 to 5 liters of blood for females
A 40 percent blood volume loss, internally or/and externally, is required to produce irreversible shock (death).
A blood loss of 1.5 liters, internally or externally, is required to cause incapacitation.
Surface Tension
The elastic like property of the surface of the liquid that makes it tend to contract, caused by the forces of attraction between the molecules of the liquid. The cohesive forces tend to resist penetration and separation.
Categories of Bloodstains
PASSIVE
TRANSFER
PROJECTED
TRANSFER BLOODSTAINS
A transfer bloodstain is created when a wet, bloody surface comes in contact with a secondary surface.
A recognizable image of all or a portion of the original surface may be observed in the pattern, as in the case of a bloody hand or footwear.
Transfer bloodstains can be further subdivided into;
Contact bleeding
Swipe or Smear
Wipe
Smudge
PASSIVE BLOODSTAINS
Passive Bloodstains are drops created or formed by the force of gravity acting alone.
This category can be further subdivided to include;
Drops
Drip patterns
Pools
Clots
TARGET SURFACE TEXTURE
Bloodstains can occur on a variety of surfaces, such as carpet, wood, tile, wallpaper, clothing, and the list goes on……
The type of surface the blood strikes affects the amount of resulting spatter, including the size and appearance of the blood drops.
Blood droplets that strike a hard smooth surface, like a piece of glass, will have little or no distortion around the edge.
Blood droplets that strike linoleum flooring take on a slightly different appearance. Notice the distortion (scalloping) around the edge of the blood droplets.
Surfaces such as wood or concrete are distorted to a larger extent. Notice the spines and secondary spatter present.
LARGE VOLUMES OF BLOOD (patterns created by same volume of blood,
from same source to target distance)
"Dripped Blood"
"Spilled Blood"
"Projected Blood" (through syringe)
PROJECTED BLOODSTAINS
Projected bloodstains are created when an exposed blood source is subjected to an action or force, greater than the force of gravity. (Internally or Externally produced)
The size, shape, and number of resulting stains will depend, primarily, on the amount of force utilized to strike the blood source.
This category can be further subdivided to include;
Arterial Spurt / Gush
Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery:
Cast-off Stains
Blood released or thrown from a blood-bearing object in motion:
Impact Spatter
Blood stain patterns created when a blood source receives a blow or force resulting in the random dispersion of smaller drops of blood.
This category can be further subdivided into;
•Low Velocity
Gravitational pull up to 5 feet/sec.
Relatively large stains 4mm in size and greater
•Medium Velocity
Force of 5 to 25 feet/sec. Preponderant stain size 1 to 4mm in size
High Velocity
Force of 100 feet/sec. and greater
Preponderant stain size 1mm in size and smaller
Mist like appearance
DIRECTIONALITY OF BLOODSTAINS
When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular.
That being the length and width of the stain will be equal.
Blood that strikes a surface at an angle less than 90 degrees will be elongated or have a tear drop shape.
Directionality is usually obvious as the pointed end of the bloodstain ( tail ) will always point in the direction of travel.
IMPACT ANGLE DETERMINATION
ANGLE of IMPACT is the acute angle formed between the direction of the blood drop and the plane of the surface it strikes
By utilizing trigonometric functions its possible to determine the impact angle for any given blood droplet.
SIN 0 = opp (a)
hyp (c)
By accurately measuring the length and width of a bloodstain, the impact angle
can be calculated using the SIN formula below
SIN < = Width (a) 1.5cm
Length (c) 3.0cm
Width (a) 1.5cm = SIN <
Length (c) 3.0cm
0.5 = SIN <
< = 30 degrees
POINT OF CONVERGENCE AND ORIGIN DETERMINATION
The common point, on a 2 dimensional surface, over which the directionality of several bloodstains can be retraced.
Once the directionality of a group of stains has been determined, it's possible to determine a two dimensional point or area for the group of stains.
By drawing a line through the long axis of a group of bloodstains the point of convergence can be determined. Where the lines of the group of stains intersect one another the convergence point can be established.
THREE DIMENSIONAL POINT OF ORIGIN DETERMINATION
WITH IMPACT ANGLE CALCULATIONS
USE OF THE COMPUTER FOR POINT OF ORIGIN CALCULATIONS
