Forensic Biology, the Toxicology Laboratory, Firearms and Toolmarks, the Medical examiner and CSI ethics.

...

trigger pull is required each time the weapon is fired. When the trigger is pulled the hammer hits the firing pin. The firing hits the cartridge causing the bullet to fire. The different parts of a Semiautomatic handgun are: the rifling (Spiraling ridges located inside the barrel), the barrel (a long tube the bullet or projectile travels through before it exits the firearm), the cartridge case (a container for all the other parts of a cartridge), the slide (the portion of a semiautomatic firearm that holds the firing mechanism), the firing pin (this initiates firing of the bullet) and the magazine (a device which holds the cartridges and feeds them one at a time into the firing chamber of the firearm).

A cartridge is a single unit of ammunition surrounded by the cartridge casing. A “blank” is a cartridge without a projectile. The different parts of a cartridge are: the primer (a shock-sensitive chemical mixture that explodes when struck by the firing pin), the cartridge case, the smokeless gunpowder (a complex chemical mixture that rapidly burns when ignited by a spark from the primer), the caliber (an approximate measurement of the bullet diameter) and the projectile (any object propelled by an explosive reaction. Bullets are specialized projectiles designed to be fast an accurate).

The bullets characteristic are: the rifling impression (impressions left on the surface of the bullet after it has been fired. They can be conventional – deep and easy to see, or polygonal – smoother and harder to see), the striations (tiny, microscopic scratches on the surface of the bullet – no two guns will produce exactly the same pattern of striations), the rifling number (the number of lands – raised areas – or grooves in a rifled barrel), and the rifling direction (it’s determined by the direction of the grooves as they move from the base to the top of the bullet).

Firearms Examiners use two types of bullet characteristics to determine if a bullet could have been fired by a certain gun: the Class Characteristics (specific for a certain brand or type of firearm), and the Individual Characteristics (specific for an individual firearm).

The bullet caliber is an example of a class characteristic. By knowing the caliber, we can rule out certain guns. Another class characteristic is the rifling number. If after ruling out certain guns using the class characteristic, there’s still a doubt in which gun was used in the crime, we will testfire each of the remaining guns in the watertank to get standards. Standards are marked with the individual characteristics of the gun that fired the bullets. The comparison microscope is used to compare the standards of the bullets. If the striations of the two bullets (the suspect and the test) are the same, the bullets were fired by the same gun.

Medical Examiner

When a dead body arrives to the morgue, the first thing a medical examiner does in an external autopsy. He looks for clues on the outside of the body. Next is the internal autopsy, where a medical examiner looks at the internal organs for signs of damage or disease. To perform an autopsy, the medical examiner needs to wear gloves, scrubs and face shield. The autopsy starts with a Y section. The next step will be to remove the rib cage and expose the inner organs. Then, he has to take some samples for the toxicology lab. Next, the organs are removed together – it’s the Rokitansky’s technique. An autopsy also involves looking at the brain for signs of trauma. Once the organs are removed from the body, they can each be studied individually in more detail. After determine the cause of death, it’s time to discover the manner of death. The manner of death describes how the cause of death occurred. There are only five choices:

- Natural

o Sudden or unexpected deaths caused exclusively by disease

o Can occur at any age

o Usually caused by: Heart diseases

 Brain/Nervous system disorders

o Seen in 38% of cases

- Homicide

o Death caused by another person, intentionally or accidentally

o Not all homicides are murders.

o Murder is determined by the court, not the Medical Examiner

o Seen in 9% of cases.

- Suicide

o An intentional, self-inflected act

o Usually preceded by psychological problems, which may or may not be on record

o Occurs in 9% of death investigations

- Accidental

o The most common manner of death (40% of cases)

o Used if death was unintentional or essentially unavoidable.

- Undetermined

o Implies uncertainty about the circumstances surrounding the death.

o Usually a temporary classification until the investigation is complete.

o Only 4% of cases use it as the final classification.

We use information from the dead body and its environment to determine the time of death. This means when a Medical Examiner or his Assistant goes to a crime scene, he’s not just there to collect the body, he also needs to observe and collect data. There are 3 important things to look for in a body: the Algor Mortis (body temperature); Rigor Mortis (Stiffening of the muscles); Livor Mortis (discoloration of the body).

If I had to choose a job that I would never do is Medical Examiner. It’s the job I would never see me doing because, even though the autopsy is one of the most important parts in forensics, it’s very hard for me to, for example, open a dead body, or remove organs from the body. And something that I would love to do is being part of the department of Firearms and Toolmarks, because it is something very mechanical and it can determine if a suspect is guilty or not. I think a job very important, and I would like to be a part of something like that.

...