Blood Spatter Test-Forensics.

General Characteristics.

-On avg. accounts for 8% of total body weight.
-4.5-5.5 liters of blood.
-Internal and or/ external blood lose(hemorrhage).
-40% blood loss produces irreversible shock(death).
-20% loss(1.5 liters) causes incapacitate(loss/impairment of consciousness and

Circulatory System. Arteries.

Carry blood away from heart, oxygenated, high pressure.

Circulatory System. Veins.

Carry blood into heart, low pressure,deoxygenated.

Heart Chambers. Right side of heart.

Functions to receive deoxygenetated blood and send to lungs to oxygenate.

Heart Chambers.Left side of heart.

Functions to receive oxygenated blood and send it to the rest of body.

Blood Pressure.

Determined by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries.More blood your heart pumps=narrower arteries=higher blood pressure.

Systolic(numerator of blood pressure).

Higher of two numbers measures the pressure in the arteries when the heart beats(When the heart contracts).

Diastolic(denominator of blood pressure).

Lower of two numbers, measures the pressure in arteries between heartbeats(When heart is resting,between beats).

Blood Loss classification due to Trauma.1)Class 1 Hemorrhage.

Involves up to 15% of blood volume.Typically no change in vital signs and no need for IV.

Blood Loss classification due to Trauma.2)Class 2 Hemorrhage.

15-30% of total blood volume. Tachycardia(Rapid Heart Beat) the systolic and diastolic blood pressure narrow range. Skin looks pale, cool to the touch. Slight changes in behavior(irritable, confused). IV, Saline solution is required.

Blood Loss classification due to Trauma.3)Class 3 Hemorrhage.

Involves loss of 30-40% of circulating blood volume. Blood pressure drops the heart rate, increases shock, mental status worsens(irritable,lethargic,diminished pain response). Blood transfusion is usually necessary.

Blood Loss classification due to Trauma.4)Class 4 Hemorrhage.

Involves of greater than 40% of circulating blood volume. The limit of body's compensation is reached and aggressive resuscitation is performed.

Estimating Blood Loss.

Visualize how much is in a pint(5 gallons is aprox. 10 pints).

Patterns of Blood stains help reconstruct crime.

1)Location.
2)Distribution.(of blood).
3)Appearance.

3 kinds of Blood Patterns(More Specific).

1)Passive-Drops due to gravity alone.
2)Transfer-Transfer of blood from one object to another.
3)Projected-Internal/external force applied to a blood source.

Passive Bloodstains.

Affected by the highest it is dropped from and if there is movement which creates an angle of impact.

Spines.

Little bumps extended from blood droplet, still attached from blood droplet.

Satellites.

Little bumps extended away from main blood droplet, not attached from droplet.

Surface Texture.

The harder, less absorptive the surface, the less secondary spatter, satellites and spines.

Shape of Stain.

Shows of direction of travel. The pointed end of a bloodstain faces the direction of its travel.

Impact Angle of blood is determined by

Measuring the circular distortion of the stain.

A drop of blood 1) is 2).

1)At right angles.
2)Circular.

Less than 1) causes the circle to 2) in shape.

1)Right angle.
2)Elongate.

What shape does blood have in flight?

Cylinder.

The angles measured are acute/obtuse?

Acute.

When blood strikes a surface from a perpendicular angle, the stain will be

90 Degrees.

Blood that strikes a surface at less 90 degrees will be

Acute angle.

When blood strikes a surface from a sharp angle, sometimes there are secondary splashes also called

Spines/Satellites.

What component of the blood spatter indicates the direction of spray?

The head of the bloodstain.

What type of math do we use to calculate AOI?

Trigonometry.

Name 2 presumptive color tests for blood.

1)Luminol/Microcrytalline.
2)Kastle Meyer.

Generally, what is the main difference between arteries and veins?Which is thicker?

Arteries are oxygenetated, veins are deoxygenetated. Arteries are thicker because they have higher blood pressure.

What chemical is important for the Kastle Meyer Test? What causes the Kestle-Meyer solution to turn pink?

Hemoglobin.

Which blood characterization tests can tell a forensic scientist what species the blood came from?

Precipition test.

What 2 factors affect your blood pressure?

1)Volume of blood.
2)Diameter of arteries.

What numbers signify normal blood pressure?

120/80.

What are 3 main types of blood splatter?

1)Passive.
2)Transfer.
3)Projected.

Give at least 2 examples of passive bloodstain patterns.

1)Passive flow pattern-When blood flows freely.
2)Passive saturation pattern-When blood flows to saturate an area(like a cloth).

What is cohesion?

It's molecules are attracted to each other, so blood sticks together as it falls.

What is adhesion?

Attraction between molecules of unlike substances affects the shape of a blood droplet.

What is surface tension?

Tension of surface from liquid caused by attraction of particles in surface layer.

With a passive drop, what shape is it in for the majority of the time it is in the air?why?

Passive flow pattern when blood flows freely due to gravity.

Contact and Collapse-

Beginning with contact with surface, the droplet begins to collapse. Collapse occurs at portion of droplet currently contacting surface while portions above remain intact, blood is pushed outward.

Displacement-

Inertia=is quality in matter that lets it stay still if its still and lets it keep moving if its moving. Spines form due to irregularities on the impact surface.

Dispersion-

It occurs of a droplet hitting at 90 degrees, satellites form @ this stage because as volume of blood in rim & protrusions become unstable.

Retraction-

Surface tension relates to blood momentum by finally overcoming the bloods momentum. Spines between satellites splatters between satellites and parent stain narrows as blood is drawn into one or the other.

How does the surface texture affect the shape of blood spatter?

The harder and less porous the surface the less spatter results.

Explain how the shape of the stain reveals info. about both direction and movement and the origin of the incident.

Must be considered when determining the direction, dropping distance and angle of impact.

What is the area of convergence?What us it useful for?

Is the point on a two-dimensional plane from which the drops forms a pattern originated(Where the lines of blood spatter meet). To identify origin.

What is the definition of transfer stain?

Created when an object with blood on it, touches one that doesn't have blood on it.

What is the difference between swipe and wipe?

-Swipe:Is created from an object leaving a bloodstain.
-Wipe:Is created from an object moving though a bloodstain.

A blood spatter that results from blood falling with only the force of gravity is a 1) blood spatter.

1)Passive.

A bloody footprint is an example of a 1) blood spatter.

1)Transfer.

When an artery is cut, the resulting blood spatter is under 1) pressure and is considered a 2) blood spatter.

1)High.
2)Arterial.

1) carry blood away from blood and 2) carry blood toward the heart.

1)Arteries.
2)Veins.

Up to what amount of blood loss would not require medical intervention or a disruption of vital signs?

15%.

What is the amount of blood loss that would require intravenous IV saline solution?

15-30%.

What are a victim's symptoms if they have lost a large amount of blood?

Skin looks pale, cold to the touch,irritable, lathargic,confused, tachycardiac.

What happens to blood pressure when a person loses large amounts of blood?

Decreases.

The artery that leaves the heart with oxygenetated blood to the body is called the

Pulmonary.

The arteries that circulate blood into the thighs of your legs are called the 1) arteries.

1)Femoral.

The arteries that supply blood to the upper arms are the 1) arteries.

1)Brachial.

The 1) blood cells carry the oxygen portion of the blood.

1)Red.

The protein component of the red blood cells that carries the oxygen and is responsible for the red color is the

Hemoglobin.

When blood is not visible at a crime scene, a 1) test can be made to determine the presence of blood.

1)Luminol.

The luminol test reacts with 1) in the 2) in the blood.

1)Iron.
2)Hemoglobin.

What is the formula for calculating the angle of a blood spatter?

sin-1(width/length.)

In an emergency, a person who is bleeding heavily from wounds will experience a loss of blood volume, a decrease in blood 1), the cells of the body will not receive 2), cells death will begin and if aid is not received the person will die.

1)Pressure.
2)Oxygen.

As the angle increases the blood spatter becomes more

Circular.

As the angle decreases the blood spatter becomes more

Elongate.

Cast-off Stains.

Blood released or thrown from a blood-bearing object in motion.(Like a bat/hammer in motion and blood spatters from a bat/hammer).

Impact Bloodstain Pattern.

Impact spatter occurs when an object impacts a source of blood.

Force.

A push or a pull on an object.
Equation:Mass times acceleration.

Velocity.

Speed with direction;ft/sec.

Acceleration.

Rate of change of velocity.

Height of Drops.

Bloodstain diameter increases with increase height.

Low Velocity Blood Spatter.

-Impact 5 ft./sec or less.
-Same concept as Passive Bloodstains.
-Large diameter of 4mm or more.

Medium Velocity Spatter.

-Impact 5-25 ft./sec or less.
-Intense beating,stabbing.
-Diameter 1-4mm.
-Force of impact cause more blood molecules to break surface tension.

High Velocity Spatter.

-Impact of 100ft./sec.
-Gunshot, extreme amount of force upon impact.
-Fire spray of tiny droplets.
-Extreme disruption of surface tension.

When investigators try to locate trace amounts of blood at a crime scene they can spray luminol and watch for a visible 1) reaction.

1)luminous.