#forensic-facts

[forensic-facts-blog]

Day 35 - Fractures or broken bones are described by their location, how the bones are aligned, whether there are associated complications with blood and nerve function, and whether the skin is intact at the injury site.

Bones are rigid, but they do bend or "give" somewhat when an outside force is applied. However, if the force is too great, the bones will break, just as a plastic ruler breaks when it is bent too far. Thus, the severity of a fracture usually depends on the force that caused the break. 

These breaks are classified by where they’re open fractures (complex fractures) or closed (simple fractures). Essentially, open fractures refer to when the bone penetrates through the skin and has a higher risk of infection whereas closed fails to breach the skin. 

Simple fractures include:

Greenstick fracture: an incomplete fracture in which the bone is bent. This type of fracture occurs most often in children.

Transverse fracture: a fracture at a right angle to the bone's axis.

Oblique fracture: a fracture in which the break is at an angle to the bone’s axis.

Comminuted fracture: a fracture in which the bone fragments into several pieces.

An impacted fracture: a fracture whose ends are driven into each other. This commonly occurs with arm fractures in children and is sometimes known as a buckle fracture.

Spiral fracture: a fracture that spirals or extends down the length of the bone

Bowing fracture: when the bone bends but doesn't break. This type of “fracture” is only seen in children. 

Fractures are also defined by anatomical terms to determine locations, these include:

Proximal (closer to the center of the body) and Distal (further from the center)

(Ex. the elbow is proximal to the wrist and the wrist is distal to the elbow)

Anterior (toward the front of the body) and Posterior (toward the back)

(Ex. The chest is anterior to the back and the back is posterior to the chest)

Medial (toward the middle of the body) and Lateral (to the outer edge of the body)

(Ex. The ears are lateral to the nose and the nose is medial to the ears)

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[forensic-facts-blog]

Day 17 - A decomposing body goes through four stages: autolysis, bloat, active decay, and skeletonization.

Decomposition begins four minutes after death as the heart has stopped beating and the cells are deprived of oxygen. Autolysis is the enzymatic processes in which cells break down due to the build up of carbon dioxide and waste products. 

Bloating becomes the second stage as the body may double in size due to the bacteria’s interaction with the soft tissue that creates a range of gases. A light yellow-green discoloration of the skin may also occur due to the sulfur-containing compounds. Body fluids begin to leak during this time and escape through any available orifice due to the pressure. Ruptures on the skin may occur and a strong smell is emitted, which will attract insects that will thus devour the flesh.

Active decay results when the tissue becomes liquefied and the smell is still present. 

Skeleonization has occurred once the body is fully decomposed. 

In addition to the various gases, a human decomposing body release approximately 30 chemical compounds, some with distinct odors. Common chemical compounds and their distinguishing smells include:

Cadaverine and putrescine - rotting flesh

Skatole - feces odor

Indole - mustier, mothball-like smell

Hydrogen sulfide - rotten eggs

Methanethiol - rotting cabbage

Dimethyl disulfide and trisulfide - garlic-like odor

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[forensic-facts-blog]

Day 32 - Forensic odontology (also called forensic dentistry or bitemark evidence expertise) mainly involves the identification of an assailant by comparing a record of their dentition (set of teeth) with a record of a bite mark left on a victim.

Forensic dentists (odontologists) examine the development, anatomy and any restorative dental corrections of the teeth, such as fillings, to make a comparative identification of a person.

In death cases, the forensic odontologist attends the autopsy and takes photographs, cranial measurements, dental impressions and x-rays from the remains. These samples are then compared to those of known missing individuals. If a match can be made, the remains can be identified.

There are several types of bite marks that are categorized by four degrees of impression:

hemorrhage — small bleeding spot

abrasion — undamaging mark on skin

contusion — ruptured blood vessel, bruise

laceration — punctured or torn skin

incision — neat puncture of skin

avulsion — removal of skin

artifact — bitten-off piece of body

More than just homicides, forensic odontologists may handle:

Identification of unknown human remains through dental records.

Assisting at the scene of a mass disaster.

Age estimations of both living and deceased persons.

Analysis of bite marks found on victims of attack.

ID of bite marks in other substances e.g. wood, leather and foodstuffs.

Analysis of weapon marks using the principles of bite mark analysis.

Presentation of bite and weapon mark evidence in court.

Building a picture of lifestyle and diet at an archaeological site.

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[forensic-facts-blog]

Day 34 - Forensic photography is producing a permanent visual record of accidents and crime scenes for use as evidence in court, and for measurement and analysis.

The purpose of crime scene photography is to document what is there and where it is in relationship to the scene, whether it is obviously connected to the crime or not.

A critical aspect of photographic quality is resolution. The term resolution in the context of photography refers to the degree to which adjacent objects can be distinguished from one another in a photographic image. Obviously, the higher the degree of resolution—which is a function of the acuity of the photographic equipment used, as well as the abilities of the operator—the better the quality of the photograph.

In this line of work, forensic photographers may be expected to: 

have a thorough grasp of photographic principles, particularly those involving non-standard techniques, such as high-intensity and low-level aerial imaging

have excellent technical skills in photo imaging

appreciate the importance of your work

take a precise approach to image and data recording

be highly organised

pay close attention to detail

use the best equipment and techniques for each different environment and lighting condition

capture images that have maximum depth of field, are free from distortion and are in sharp focus

have a solid grounding in police methods

possess a sound understanding of anatomy

take images that record the appearance of physical evidence without appealing to the emotions of those judging a case

keep detailed records of the location the image was taken, the type of camera and lens used, and whether flash or artificial lights were used

have good communication skills in dealing with a wide range of professionals

demonstrate tact and discretion in dealing with victims of crime

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[forensic-facts-blog]

Day 25 - Forensic Archaeology is the specialist application of archaeological techniques to the search and recovery of evidential material from crime scenes, often but not always related to buried human remains.

The main tasks that a forensic archaeologist assists with are: 

Evidence searches 

Evidence recovery 

Evidence recording  

Scene interpretation

A forensic archaeologist’s first involvement may be to help the police locate the site where a body and victim’s personal items, or stolen goods are buried, through geological and geophysical surveying techniques, as well as using imaging and photography.

The forensic archaeologist may assist with the excavation by using similar tools and expertise to those used at an archaeological dig. This has to be done slowly and painstakingly, and the archaeologists will record and preserve anything found at every stage and depth (for example paint flakes, hair, clothing or DNA) as it may be vital evidence. 

Most sites have become incorporated into the archaeological record and require subsurface archaeological recovery techniques, such as stratigraphy or the analysis of layers of soil in accordance to their time period. 

Other general principles followed by forensic archaeologists include: 

Law of Superposition - A stratigraphic unit that underlies another must be older than the overlying unit (older is below younger layer)

Law of Inclusion - Any item (or evidence) contained within a deposit must be older than the deposit and the process by which the deposit was laid down. (ex. bricks in a wall are older than wall itself)

Law of Association - The nature of the chronological and spatial relationship between two objects within a stratigraphic unit is determined by the integrity of that stratigraphic unit. ( Items or evidence found in close proximity in the same deposit are assumed to be associated)

Law of Crosscutting Relations - Any feature that intrudes into a deposit must be younger than the deposit into which it intrudes. (ex. A grave is always younger than the soil into which it is dug)

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[forensic-facts-blog]

Day 29 - Forensic medicine, otherwise known as legal medicine or medical jurisprudence, is a branch of medicine that interprets and establishes the medical facts in civil or criminal law cases. 

The use of medical testimony in law cases predates by more than 1,000 years the first systematic presentation of the subject by the Italian Fortunatus Fidelis in 1598. Forensic medicine was recognized as a specialty early in the 19th century.

Areas of medicine that are commonly involved in forensic medicine are anatomy, pathology, and psychiatry.

Forensic medicine typically involves cases concerning:

blood relationships

mental illnesses

injuries 

death(s) resulting from violence

Forensic Medicine also provides us with clues to our ancestry with tests being carried out on Mitochondrial DNA - that strand of DNA that is passed down through the generations between bloodlines.

MtDNA is a small circular genome located in the mitochondria, which are located outside of a cell's nucleus. Most human cells contain hundreds of copies of mtDNA genomes, as opposed to two copies of the DNA that is located in the nucleus. This high copy number increases the likelihood of recovering sufficient DNA from compromised DNA samples, and for this reason, mtDNA can play an important role in missing persons investigations, mass disasters, and other forensic investigations involving samples with limited biological material.

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[forensic-facts-blog]

Day 19 - Forensic Entomology is the use of insects, and their arthropod relatives that inhabit decomposing remains to aid legal investigations.

Forensic Entomology is typically broken down into three different areas: 

Medicolegal: focuses on necrophagous or carrion insects that feast on human remains

Urban: focuses on insects that feast on both dead and living flesh, whose bites may be confused with abuse 

Stored product pests: focuses on insects that are commonly seen in food, which may indicate food contamination.

It is by collecting and studying the insects that are feeding on a body that a forensic entomologist can estimate the time elapsed since the person died. Investigators can determine this from insects by studying the development of the insect.

Forensic entomologists can also help to establish a portion of the postmortem interval (which is known as the period of insect activity, or time since colonization), assist in establishing the geographic location of death in cases of body transport, help associate the victim and suspect to each other and to the scene, and help the pathologist identify sites of trauma on the corpse. 

Additionally, entomologic evidence can be utilized as alternate toxicology samples, and their gut contents can be sources of human DNA viable for forensic testing.

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[forensic-facts-blog]

Day 15 -  Sex can be determined from the bone structure of a human skeleton. 

In order to determine sex from skeletal remains, anthropologists may look at the pelvis, skull, sternum, scapula, or femur to estimate if they belong to a male or female. 

This includes but is not limited to:

Pelvis 

   Male: 

narrower, heart-shaped pelvic inlet

narrower sciatic notch

narrower angle where the two pubic bones meet in front

prominent muscle ridges

sub-pubic angle is V-shaped and less then 90 degrees

pubic bone is typically more triangular

the acetabulum (hip socket) is larger and more lateral

the obturator foramen is more egg-shaped

sacrum is long and narrow

illium is vertical

   Female: 

open, circular pelvic inlet

broader sciatic notch

wider angle where the two pubic bones meet in front

more outwardly flared hip bones

sub-pubic angle is U-shaped and 90 degrees or higher 

pubic bone is typically more rectangular

the acetabulum (hip socket) is smaller and more anterior

the obturator foramen is more triangular

the sacrum is short and broad

illium appear lower and flares out

Skull

   Male: 

forehead is more slanted

supraorbital ridges are more pronounced

zygomatic arches bow outward

rounded orbital margins

larger glabella

larger maxillary bones (cheek bones)

nasal aperture is higher, narrower, and its margins are sharp rather then rounded

the nasal bones are larger and meet in the midline at a sharp angle

mastoid process is larger

external occipital protuberance

mandible is thicker and larger

larger condyles, square chin

U-shaped oral cavity

larger foramen magnum 

   Female: 

forehead is more rounded

frontal and parietal eminences are more pronounced

zygomatic arches remain medial

eye orbits are higher, more rounded and larger with sharp orbital margins 

more slender maxillary bones (cheek bones)

occipital region is smoother

Parabolic oral cavity

Sternum, Scapula, and Femur

   Male: 

body is twice the length of the manubrium (sternum)

deep supra-scapular notch (scapula)

femur is larger and heavier

   Female: 

narrow supra-scapular notch (scapula)

angle of the neck to the shaft in the femur is greater

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