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Forensic Science > Blood Spatter > Flashcards

Blood Spatter Flashcards

1
Q

Define the following term:
Blood spatter:

A

patterns made when blood strikes a surface

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2
Q

Define the following term:
Satellite spatter:

A

small droplets of blood that occur around the perimeter of a larger blood drop

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3
Q

Define the following term:
String method:

A

method used to find the areas of convergence and origin to determine where a bloody impact occurred

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4
Q

Define the following term:
Impact spatter:

A

spatter produced when an object impacts a source of blood; most common type of blood spatter found at crime scenes

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5
Q

Define the following term:
Cast off spatter:

A

spatter created when a blood covered object flings blood onto a surface between blows

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6
Q

Define the following term:
Area of convergence:

A

the point on a 2 dimensional plane from which the blood drops originated

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7
Q

Define the following term:
Area of origin:

A

the area in a 3 dimensional space from where the blood originated

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8
Q

Define the following term:
Angle of Impact:

A

the angle at which a blood drop strikes a surface

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9
Q

Define the following term:
Forward spatter:

A

blood spatter that is projected out and away from a source of blood

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10
Q

Define the following term:
Back spatter:

A

blood spatter projected backwards from the source of blood; can be projected back onto the person delivering the blow

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11
Q

Define the following term:
Drawback effect:

A

back spatter than can end up inside the muzzle of a gun

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12
Q

Define the following term:
Aterial spray/spurt:

A

spatter created when a person suffers an injury to a major artery or the heart

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13
Q

Define the following term:
Expirated blood:

A

pattern created by blood expelled through the mouth and nose due to a serious internal injury; often pink in color and has bubbles due to mixing with saliva

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14
Q

Define the following term:
Void pattern:

A

pattern created when an object or person blocks blood spatter; can be seen when object is then removed

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15
Q

Define the following term:
Contact or transfer stain:

A

pattern produced when a blood covered object touches another surface that does NOT have blood on it

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16
Q

Define the following term:
Flow:

A

pattern made when a drop or a large amount of blood is being pulled by gravity

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17
Q

Define the following term:
Pool:

A

pattern made when a large quantity of blood is on a level surface

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18
Q

Define the following term:
Skeletonization:

A

how blood “dries”; starts on the outside of a stain; due to coagulation from clotting factors, etc.

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19
Q

Define the following term:
Trail pattern:

A

produced when blood is passively dripping from a wound or blood covered weapon while the person is moving (and carrying the weapon). Can lead to a suspect or a discarded weapon.

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20
Q

What are 4 common types of physical evidence on which blood spatter can be found?

A
  1. floors
  2. walls
  3. ceilings
  4. bedding
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21
Q

Blood dropping from a 90o angle will produce what shape of drop?

A

circular

22
Q

Blood hitting a surface at an angle OTHER than near 90o angle will produce what type of shape?

A

Elliptical. The farther the angle is away from 90 degrees, the more elliptical the drop

23
Q

What are 12 possible things that can be learned from examining blood spatter at a crime scene?

A
  1. the direction from which the blood originated
  2. the angle at which the blood struck the surface
  3. the position of the victim when he/she received the blows
  4. the minimum number of blows that struck the victim
  5. the approximate position of the person delivering the blows
  6. the type of injuries inflicted (sharp force versus blunt force)
  7. the order in which the wounds were inflicted
  8. whose blood is present (using DNA)
  9. the type of weapon used
  10. the position/movements of victim during blows (sitting, running away, etc)
  11. whether the victim was moved post assault
  12. the distance the blood was dropped before hitting the surface
24
Q

How is it possible to determine which way a blood drop was traveling?

A

In elliptical shaped stains, examine the tail. The tail always points TOWARDS the direction of travel.

25
Q

What are the three types of impact spatter and what types of injuries are associated with each type?

A
  1. low velocity: produced with minimal force; example….blood passively dripping from a wound
  2. medium velocity: produces stains with a diameter of 1-3 mm; usually associated with blunt force trauma like a beating
  3. high velocity: produced by high force and velocity; stains are very small like “pin pricks”; associated with gunshot wounds and explosives
26
Q

What are the three types of calculations (in order) involved in determining the origin of impact?

A
  1. angle of impact
  2. area of convergence
  3. area of origin
27
Q

What are three things that can be determined from examining a cast off spatter pattern?

A
  1. can determine the number of blows
  2. can determine what type of weapon was used
  3. can determine if the offender was right handed or left handed
28
Q

What are four types of contact/transfer patterns?

A
  1. fingerprints
  2. footprints
  3. toolprints
  4. fabric patterns
29
Q

What is the difference between an active flow and a passive flow?

A

An active flow occurs when a person is alive and the blood is flowing from an actively bleeding wound; a passive flow is when blood is deposited on a non-level surface.

30
Q

Fill in the blanks: Bloodstain patterns may convey to the analyst the location and movements of both the
__________ and _____________ during the commission of a crime.

A

victim
assailant

31
Q

True or False: Harder and less porous surfaces result in less spatter, whereas rough surfaces result on stains with more scatter and serrated edges.

A

True

32
Q

A drop of blood that strikes a surface at an angle of impact of approximately 90 degrees will be close to (elliptical or circular) in shape.

A

Circular

33
Q

The angle of impact of an individual bloodstain can be estimated using the ratio of _________ divided by _____________.

A

Width
Length

34
Q

__________ is the most common type of blood spatter found at a crime scene, and is produced when an object forcefully contacts a source of blood.

A

Impact Spatter

35
Q

The classification system of impact spatter is based on the size of droplets resulting from the velocity of the blood droplets produced, and patterns can be classified as __________, ____________, or ____________ impact spatter.

A

Low
Medium
High

36
Q

The _________________ is the point on a two dimensional plane from which the drops originated.

A

Area of convergence

37
Q

The ________________________ of a bloodstain pattern in a three-dimensional space illustrates the position of the victim or suspect when the stain-producing event took place.

A

Area of origin

38
Q

The ____________________ method is used to determine the area of origin.

A

Stringing

39
Q

Movement of a bloody object across a surface (circle one: lightens or darkens) as the pattern moves away from the point of contact.

A

Lightens

40
Q

True or False: The direction of a flow pattern may show movements of objects or bodies while the flow was still in progress.

A

True

41
Q

The edges of a bloodstain will generally _________ within 50 seconds of deposition and be left intact even if the central area of a bloodstain is altered by a wiping motion.

A

Dry

42
Q

A ___________________ pattern commonly originates from repeated strikes from weapons or fists and is characterized by an arc pattern of separate drops showing directionality.

A

Cast off

43
Q

True or False: Characteristics of a cast-off pattern cannot give clues as to the kind of object that was used to produce the pattern.

A

False

44
Q

When an injury is suffered to an artery, the pressure of the continuing pumping of blood projects blood out of the injured area in spurts creating a pattern known as _____________________.

A

Arterial spray

45
Q

If a ________________ pattern is found at a scene, it may show movement, lead to a discarded weapon, or provide identification of the suspect by his or her own blood.

A

Contact/transfer
Trail

46
Q

A bloodstain pattern created by _______________ features bubbles of oxygen in the drying drops and may be lighter in color when compared to impact spatter.

A

Expirated blood

47
Q

The shape and size of the blank space or ________________, created when an object blocks the deposition of spatter onto a surface and is then removed may give a clue as to the size and shape of the missing object or person.

A

Void

48
Q

True or False: A reasonable percentage of the bloodstain patterns found at a crime scene should be noted, studied and photographed.

A

True

49
Q

True or False: The tail of a bloodstain always points toward its direction of travel.

A

True

50
Q

A detective arrives at a murder scene and finds the body of a victim who suffered a gunshot wound, but sees no blood spatter on the wall or floor behind the body. What can the detective conclude from this observation?

A

The detective might conclude that:
The bullet did not exit the victim’s body, which could explain the lack of blood spatter on the wall or floor behind the body.
If the bullet did exit, another object or surface (such as clothing, furniture, or a person) may have obstructed the spatter, preventing it from reaching the wall or floor.
The position of the body or the angle of the shot may have resulted in blood spatter being directed elsewhere or absorbed by nearby surfaces, limiting visible spatter in that specific area.

51
Q

An investigator arrives at an assault scene and finds a cast-off pattern consisting of tiny droplets of blood in a very linear arc pattern on a wall near the victim. What does this tell the investigator about the weapon used in the crime?

A

The investigator can infer that:
The weapon used was likely a blunt or sharp object that could be swung repeatedly, such as a knife, bat, or club.
The small, linear, arc-like droplets suggest the weapon was swung in a repetitive motion, indicating multiple blows, which created a cast-off pattern from the weapon as it moved back and forth.

Forensic Science (9 decks)

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