Criminalistics Final

What is a Serum Stain?

What is a mass disaster?

Can be any incident greater than the resources of the region where it occur

What are findings of strangulation?

• Manual Finger Marks

• Ligature mark transverse

• Can be marked by the appearances of petechial hemorrhages on the conjunctiva

What does blood do?

• It carries oxygen and nutrients throughout the body

• it coagulates after 20-30 minutes

• Carries metabolic waste away from cells

What is a shotgun entrance wound?

Typical Gunshot Wound Entrance:

·      Star Shaped (very unique)

·      Tangential entrance – bullet coming in sideways

·      Irregular entrance due to a ricochet bullet

·      Irregular wounds due to the intermediate target

KNOW ATYPICAL WOUNDS EXIST AS WELL!

Gunshot wounds, Atypical Exit:

·      Simulating entrance

·      Shoring effect

·      Skin defect

·      Rim of ebrasion

Pellet wounds will appear all over skin if shot from far area

What about wounds show caliper?

dimensions of the wound

What is a loose contact wound?

• Produced when the muzzle of the weapon is held in very light contact with the skin at time of bullet discharge

• would show that gun powder around the skin not indented by the muzzle (no muzzle imprint)

What does a distance wound look like?

wound of entrance without surrounding tissue

lacking powder residue

Usually exhibit a hole roughly the caliber of the projectile fired.

What is seen in an exit wound?

Can be any shape

No ring of abrasion

No surrounding residue

No skin defect

What is blunt force trauma?

• Trauma caused by a blunt instrument

• Most common variety of trauma

• Can be Lethal, or non-lethal

What are the different types of blunt force trauma?

Types of B.F.T:

·      Abrasions (scratches/scrapes) – disruption of the outermost layer of the skin produced by friction – scraping, direct pressure, or rubbing. Leave no scar upon healing (road burn, brush burn.)

·      Contusions (bruises) – disruption of the underlying soft tissue without interruption of the surface. Follows compression, resulting in stretch rupture of blood vessels (black and blue marks) – Black eye,

·      Lacerations (tear) – disruption of the full thickness of the skin due to stretching.

 

Difference between laceration and shar instrument wounds (incised an stab wound):

Laceration:	Incuse and Stab Wounds
-       Irregular boarder -       Contusions of the edges -       Tissue bridging inside the wound -       Undermining of the edges	-       Sharp border -       Non-contused edges -       No tissue bridging -       No-undermining

What is a sharp force injury object?

What is a stab wound?

Stab wounds or puncture wounds are penetrating injuries whose depth within the body is much greater than the dimensions of the wound on the body surface.

• Superficial scratch is NOT a stab wound

• A stab wound HAS to go through the artificial surface

 

STAB WOUND IS DEEPER THAN IT IS LONG

is the penetration of the skin/body by a sharp or pointed instrument

What will wounds tell you about sharp objects?

The Characteristic of a stab wound:

·      The knife’s dimensions: a pathologist can aid investigation of a homicide by describing the probably type of knife used in the attack

·      A knife found at the scene can be examined alongside the wound and may indicate if its consistent with the wound

 

Taper of the blade:

Related to wound size

·      Single edge - Top part wider to the bottom (one end flattened, one end pointed)

·      Double edge – hunting or assault knife which allows best possible cutting of the body

What are muzzle impressions?

muzzle imprints

formed when the force of the gases entering below the skin blow the skin surface back against the muzzle of the gun

How does Rh factor effect pregnancies?

What factors help with estimating time since death (oh Wow)?

• Temperature (algor mortis)

• Decomposition

• Food digestion

• stiffness (rigor mortis)

• settling of the blood (livor mortis)

• Circumstantial evidence, potassium, level in eye fluid

• Skeletonization

What is different in the components of blood

What is the survival time before death?

• the period of time between the incident

• (injury/illness) and death

• the longer you wait, the harder it is to identify time of death

How can you differentiate Lividity vs. Bruising?

Blanching is?

Lividity is?

distinguished from bruising if you cut the skin and liquid pours out (Cut the tissue)

Mistaken for bruising/trauma

How long after death will blood coagulate?

How do you estimate time of death?

What is the window of death?

How do you take body temps?

What is algor mortis?

Algor Mortis —> Temperature

temperature of body raises 1-20 degrees during the first hour and then after that, loses 15.2-2 degrees h/r after death until body reaches ambient temperature

Fat (Faster)

Child (faster)

Clothing (slower)

Humidity (increases evaporation)

Immersion in water or organic substance (slows consumption)

What effects algor mortis?

What is Newton’s law of cooling?

The rate of cooling is directly proportional to the temperature differences between an object, and its surroundings (environment), provided this distance isn’t too large.

Who can pronounce you dead?

Can different stomach contents estimate Time of death?

How does the victim’s blood transfer in shootings?

Blood type question?

Genetic Question?

What is forensics?

How does blood splatter effect forensics?

What enzyme is tested for when trying to detect blood?

Who’s the daddy?

How do you process a crime scene?

What is the medulla index

What is a legal cause of death?

What is rohypnol?

What is the fingerprint template?

What can differentiate a man-made fiber?

What is a drug?

What is low-velocity blood spatter?

What is the formula for blood spatter analysis?

What different things will blood stains explain?

• origins of blood stains/spatter

• Position of the victim at the time of the blows

• Number of blows

• Direction of deposit

• Manner of disposition (drips, BFT, gunshot wounds).

• Direction of Travel after injury

What is high velocity blood spatter?

guns —> sneeze 100 ft/sec explosion

What laws do blood spatter follow?

Bullet Anatomy - Primer

Made up of what three components:

1.     Lead

2.     Barium

3.     Antimony

Typical Entrance Wound

·      Skin defect (piece of tissue is gone, never coming back)

·      Rim of abrasion

·      Surrounding residue

·      Surrounding discoloration due to CO

Abrasion Ring

Formed when the force of the gases entering below the skin blow the skin surface back against the muzzle of the gun - muzzle imprint

Range of Fire

Distant - wound of entrance without surrounding residue (around 36 inches away)

Can you determine the firearm by the wound size?

NO.

Mechanical Asphyxia

o   Including strangulation, which can be marked by the appearance of petechial hemorrhages on the conjunctiva

o   However, such finding is not specific for this injury and can be seen with other conditions

o   Finding ligature marks on the neck, hyoid bone fracture, and/or soft tissue hemorrhages in neck and larynx may help to determine the mechanism of injury (TEST QUESTION)

Livor Mortis

·      Which means literally “the color of death”

·      Is the discoloration of the skin caused by the flow of blood into the venous spaces under the influence of gravity

·      Simply put, it is the blood pooling or settling into the lowest portions of the body

·      The onset of livor mortis is immediate

·      It is well manifested in 2-4 hours

·      It is at its maximum in 8-12 hours

 

(TEST QUESTION) Coagulation stops 20-30 minutes after death (all the blood in your body will never clot again)

How can you tell the difference between Livor Mortis vs. Antemortem bruises

Tell the difference by cut tissue

Algor Mortis

Based on - Newton’s Law of Cooling 

o   The rate of cooling of an object is proportional to the temperature difference between the object and it’s surroundings, provided that this difference is not too large.

Mortis’s in order

1. Livor

2. Rigor

3. Algor

For blood spatter the angle of impact…