Chapter 4: Crime Scene Reconstruction

Question 1

What is crime scene reconstruction?

Answer 1

Crime scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime.

Question 2

What are some things that bloodstain patterns can tell us?

Answer 2

• The direction from which blood originated
• The angle at which a blood droplet struck a surface
• The location or position of a victim at the time a bloody wound was inflicted
• The movement of a bleeding individual at the crime scene
• The approximate number of blows that struck a bleeding victim
• The approximate location of an individual delivering blows that produced a bloodstain pattern

Question 3

What are the 4 main things to consider when analyzing a bloodstain?

Answer 3

• Surface texture
• Shape
• Size
• Location

Question 4

The pointed end of a bloodstain always tells you…

Answer 4

it direction of travel

Question 5

What is the formula to calculate the angle of impact?

Answer 5

Sin a = width of blood stain / Length of blood stain

Question 6

What are the 2 types of bloodstain spatter patterns?

Answer 6

• Forward spatter
• Back spatter (blowback)

Question 7

What are the 3 types of velocity splatters?

Answer 7

Low, medium, high

Question 8

What type of velocity splatter is this? Swinging of a bat

Answer 8

medium

Question 9

What type of velocity splatter is this? Standing there and just bleeding out.

Answer 9

Low

Question 10

What type of velocity splatter is this? Bullet shot

Answer 10

High

Question 11

What is the area of convergence?

Answer 11

the point of a two-dimensional plane from which the drops in an impact pattern originated

Question 12

what is area of origin?

Answer 12

The area of origin of an impact bloodstain pattern is the area in a three-dimensional space from which the blood was projected

Question 13

Whats the main difference between area of convergence and area of origin?

Answer 13

2D vs 3D

Question 14

Using lines, how you establish the areas of origin?

Answer 14

The string method is commonly used at a crime scene to approximate the position of the area of origin using found angles of impact of individual stains in the pattern.

Question 15

Using lines, how you establish the areas of origin?

Answer 15

This can be established by drawing straight lines through the long axis of several individual bloodstains, following the line of their tails

Question 16

Give an example of forward and back spatter.

Answer 16

Shooting someone and blood coming back on the shooter is back spatter, but blood getting on the wall behind the victim is forward spatter.

Question 17

Is forward spatter always produced?

Answer 17

Not when there isn’t an exit wound.

Question 18

What is cast off spatter?

Answer 18

A cast-off pattern is created when a blood covered object flings blood in an arc onto a nearby surface.

Question 19

What is an Aerial Spray Spatter?

Answer 19

Arterial spray spatter is caused by an injury to the heart or a main artery and the pressure of the continuing pumping.

The site of the initial injury is found where the pattern begins with the biggest spurt. The trail away from this point shows the victim’s movement.

Question 20

What is an Expirated Blood Pattern?

Answer 20

An expirated blood pattern is created by blood that is expelled from the mouth or nose from an internal injury.

Question 21

What can expirated blood patterns tell us?

Answer 21

The presence of expirated blood gives an important clue as to the injuries suffered and the events that took place at a crime scene.

Question 22

What is a void pattern?

Answer 22

A void is created when an object blocks the deposition of blood spatter onto a target surface or object, and the spatter is deposited onto the object or person instead.

Question 23

What is a contact or transfer pattern?

Answer 23

A contact or transfer pattern is created when an object with blood on it touches one that does not have blood on it.

Question 24

What is Skeletonization?

Answer 24

The phenomenon of skeletonization occurs when the edges of a stain dry.

Question 25

How long does it take for skeletonization to occur?

Answer 25

About 50 seconds

Question 26

What are the 2 techniques used to document bloodstain patterns?

Answer 26

• Grid method
• Perimeter rule method

Question 27

What are the extra dots around the center of a bloodstain called?

Answer 27

Satellites

Question 28

What to hemosticks do?

Answer 28

Chemical on stick will change to pink when it’s blood