Forensics Rest

handguns

Started as single-shot pistols with no trigger guards, then went to derringer type, where the hammer is pulled back, but there is still no trigger guard. Then there were revolvers that have a hammer to pull back, and the trigger had a guard. It has a cylinder with 5-6 cartridges and a front/back sight. There is a handle for the individual to hold. The cylinder latch releases the chamber, the brass and casing are not discharged; you have to use an ejector to take them out. The bore (looking down the weapon) gives the caliber. Then there were automatic pistols which has no hammer. It does have a trigger and guard with an ejection port and rear sight. There is a contact range discharge, a real coil spring guide rod. The magazine is held in the handle of the gun, and as you fire, the brass is ejected. These are usually found at the scene unless they are picked up.

rifles

Firearm with rifled barrel designed to be fired from the shoulder. U.S. federal law requires them to have a minimum barrel length of 16 inches. Single-shot, lever-action, bolt-action, pump-action, and auto-loading. Lands and grooves on the bore imparts spin on the bullet that allows for more precision and accuracy. Scope, longer, bolt action, single-shot, or magazine. Each time you fire, you have to take the bolt and bring it back, then eject the casing and then insert the next bullet or the next bullet just comes up).

submachine guns

Firearm designed to be fired from the shoulder and/or hip, capable of automatic fire. Rifled barrel. Fires pistol ammunition. Usually not legal for civilians in the U.S. looks similar to automatic loading handguns

machine guns

Capable of full-automatic, fires rifle ammunition, usually belt-fed. Crew or single individual operated. 50 caliber is the largest type of ammunition.

shotguns

Firearm designed to be fired from the shoulder, usually smooth bote that fires multiple pellets, can fire a single projectile known as a slug and may have a rifled barrel. U.S. law requires minimum barrel length of 18 inches. Single shot, skeet, semi-automatic (autoloaded).

caliber

Rifled weapons have spiral grooves that cut the length of the bore of the barrel with metal between them. Grooves are the distance from metal piece to metal piece (land to land) and roughly equate to this.

gauge

describes the caliber of a shotgun, only which is the number of lead balls of the given bore diameter that make up a pound. For example, if it takes 12 lead balls that are the diameter of the bore, the shotgun is considered a 12-gauge. The lower the gauge, the larger the bore. However, .410 describes the inches from one side of the bore to the other and is an exception.

basic parts of ammunition

• Cartridge case

• Primer

• Propellant (gunpowder)

  • Helps to make exothermic reaction that pushes the bullet forward

• bullet/projectile

  • Full jacker, semi, or soft point

  • Indicates interaction of bullet with target

  • How it hits may make a difference in wound/injuries that occur

discharge of a weapon

When the trigger is pulled, the firing pin is released, this strikes the primer and ignites it causing a large flame to be produced. The flame ignites the gunpowder and produces gas/heat.

entrence wounds

Tearing/moving of the skin and soft tissue behind it, permanent cavity caused by damage to the tissue, perpendicular to the skin, stretch it and abrasion to the skin (“abraision collar”). Rifle rounds give small spicules around the hole “micro tears” need high velocity and spin rate. Some don’t leave abrasions at all.

exit wounds

usually lacerated, may not have the same width as the entrance wound. Just pushing tissue out. Bullet may be tumbling in the body so the exit wound may not have the same orientation. A short exit can look like an entrance.

stippling

Puntate abrasions, as the weapon moves further away, these become more sparse with less gunpowder, can’t say which was the first or the time between the two.

abrasion ring

Often seen from distant or intermediate wounds. It is identified by stretching of the skin and causing an abrasion to form around the cavity the bullet entered through.

soot

comes out of handguns and revolvers, so if this is present, the handgun was likely in close proximity to the deceasesd. There also may be accompanying abrasions.

muzzle stamp

This is caused by the gun being pressed up against someone while the firearm is fired. It is often seen in things like suicide.

searing

This is seen in contact GSWs because it means the firearm was touching the skin. When the firearm fires, it is very hot and can cause this.

evidence in autopsy suite

risk of contamination, tampering, and ensuring the integrity of the investigation.

circumstances of Lincoln’s autopsy

Ford’s Thearer on 14 April 1865 there was a shot heard from behind the President’s box, to the right of the stage. A man then leaped down from the box to the stage, catching the spur of his riding boot on the flag, brandished a knife then ran off the stage. The President was found unresponsive with a gunshot wound to the head and taken to the house opposite of theater where he died the next morning. Evidence collected at the scene consisted of derringer, spur, and an assassin’s cap

evidence of injury Lincoln’s autopsy

GSW to the head, the entrance was the back of the head with blackened wound edges. He injured his scalp, occipital bone (½ inch round defect with internal beveling), dura mater, and brain. There was no exit wound. A deformed projectile was recovered in the anterior cerebral hemisphere of the brain behind the eye. Lead fragment and bone fragments were found along the wound track. The trajectory of the bullet was back to front, left to right, and upward. He had associated injuries of fractures of both orbital plates, bilateral perioribital ecchymoses, subdural hemorrhage, subarachnoid hemorrhage, intraventricular hemorrhage, and hemorrhage along the wound track.

Lincoln’s autopsy conclusions

COD: GSW wound of the head

MOD: homicide

Evidence of close range discharge from a fire arm (blackened wound edges)

Lincoln’s chain of custody

Evidence: projectile, lead fragment, and bone fragments were placed in the possession of the doctor (Dr. Stone). Sealed and marked in the presence of the Secretary of War (Mr. Stanton) and the proble used to determine the length of the wound track was sealed and turned over to Secretary Stanton.

low order explosion

deflagration and subsonic speeds

high order explosion

pressurized gas at supersonic speeds with a shock/blast wave and blast wind

primary blast injuries

Direct result of impactof the black wave upon the body, rupture tympanic membranes (moves back and forth and goes through 3 small bones, puts that in neurons to allow hearing, hard to see) and can lose hearing. Tympanic membranes should be white and reflect light from the otoscope. Get abdominal injuries, blast lung injuries (pneumothorax - holes in the lungs, hemmorhage - bright appearance on X-ray, or looks contused), amputations, and body fragmentation.seco

secondary blast injuries

Result from flying debris (rocks, glass, wood and bomb fragments energizeed by the explosion). Usually have penetrating traima (ball bearing, can hit individual in the heart, fractures - no metallic artifact but could be a rock, glass fragments - superficial or underlying).

tertiary blast injuries

Result of the body striking an object and getting blunt force trauma, unless it is a sharp object. Some injuries include subarachnoid hemorrhage, cervical spinal cord fracture, or vertebral column fracture. The lower spine can hit the ground as well.

quaternary blast injuries

All explosion-related injuries, illnesses, and diseases not due to the above categories. These injuries consist of thermal and chemical burns, inhalation injury, radiation exposure, and exacerbation of chronic disease (can be a contributing factor in death if not dead from the explosion)

wilhelm conrad Roentgen

He noted fluorescence of a screen coated with barium plantinocyanide. The rays penetrated paper, cloth, plank, and book. Metals were opaque. Developed fluorescent screen with photographic plate. He produced and detected electromagnetic radiation in X-ray wavelength. Where X stands for unknown.

4 types of radiologic imaging modalities

Fluoroscopy, computed and direct digital radiography, computed tomography (CT), and magnetic resonance imaging (MRI).

fluoroscopy strengths

ability to visualize objects “real-time”, detect vascular injury with injection of contrast, and the ability to produce hard-copy of image. It also has a relatively low cost.

fluoroscopy weaknesses

limited field of view, image archive, increased radiation

digital radigraphy strengths

identify skeletal fractures and foreign objects and has digital storage and retrieval

digital radiography weaknesses

reposition body for “whole body” radiograph, overlapping fractures, multiple views needed to “locate” foreign body, identification of soft tissue injury, may need radiology technician

computed tomography strengths

single scan of the entire body, digital storage and retrieval, precise location of foreign object, ability to convert 2D images to 3D, visualize some natural diseases.

computed tomography weaknesses

resolution of soft tissue injury and surface wounds, increased cost of machine and maintenance, need radiology technician

MRI strengths

increased resolution of soft tissue injuries, digital storage and retieval, ability to convert images from 2D to 3D

MRI weaknesses

increased time to acquire images, movement of metallic fragments during scan, relatively high cost of machine installation and maintenance, need a radiologist/radiology technician

Mass (complex) fatality incident

Defines incidents as natural or man-made: weather related, toxic environment, infectious disease, transportation mishaps, fires and explosions, random acts of violence and mass homicides, acts of terrorism. They are described as incidents where the local resources that are normally used in response to a fatal incident are overwhelmed or have the potential to be overwhelmed

role of coroner/ME in mass fatality incidents

Forensic pathologist investigation consists of jurisdiction, scene, identification, autopsy examination, collection/transfer of evidence, cause of death, manner of death, final report, and death certificate. They may also deal with public health concerns of contamination and long-term effects.

Container

C in CREEP

restraints

R in CREEP

environment

first E in CREEP

energy absorption

second E in CREEP

Post-crash factors

P in CREEP

Causal, contributing, coincidental

Three C’s of aviation mishap investigations when looking at natural disease present during incident

vertebral fractures/compressions

injuries at 15-30 g

pulmonary contusions

injuries at 25-30 g

rupture of A-O membrane

injuries at 30-35 g

laceration of aorta

injuries at 50+ g

transection of aorta

injuries at 80 + g

skull fractures and pelvic fractures

injuries at 100+ g

vertebral body transection

injuries at 200+ g

fragmentation

injuries at 300+ g

pattern injuries

correlate to the mechanism of injury and demonsrtate characteristics of the object that interacted with the occupant. An example is a shoe print.

control surface injury

There is a theory that crash forces are directed through the aircraft structure and controls directly to the hands of the individuals actively trying to control the aircraft, resulting in injury (predominantly fractures). Have to rule out pilot incapacitation and determine who was in control at the time of the mishap.

bottle to throttle rule

Mandates that pilots abstain from alcohol consumption for a minimum of eight hours before taking control of an aircraft, the FAA recommends 24 hours. This is to ensure that pilots are not impaired by alcohol or hangover effects that can negatively impact flight safety.