Advanced Forensics Flashcards

Questions and Answers

What is an accompanying drop?

A bloodstain with characteristics of a physical change.

A small blood drop produced as a by-product of drop formation. (correct)

The area containing intersections generated by blood stains.

The angle at which a blood drop strikes.

What does altered stain indicate?

A bloodstain with characteristics that indicate a physical change has occurred. (correct)

A blood drop that fell onto a surface.

A stain caused by insect activity.

A potential change in temperature.

What is the angle of impact?

The acute angle (alpha) at which a blood drop strikes a target.

Define area of convergence.

The area containing the intersections created by lines drawn through the long axes of individual stains. Signup and view all the answers

What is the area of origin?

The three-dimensional location from which spatter originated. Signup and view all the answers

What does a backspatter pattern indicate?

Bloodstain pattern resulting from blood drops that traveled in the opposite direction of the force applied. Signup and view all the answers

A bloodstain is a deposit of blood on a _____

surface. Signup and view all the answers

What does a bloodstain pattern indicate?

It indicates through regular or repetitive form, order, or arrangement how the stain was deposited. Signup and view all the answers

A bubble ring is an outline within a bloodstain resulting from air in the blood.

True Signup and view all the answers

A saturation stain results from the accumulation of liquid blood in an _____ material.

absorbent. Signup and view all the answers

What is a drip pattern?

A bloodstain pattern resulting from a liquid that dripped into another liquid, at least one of which was blood. Signup and view all the answers

What is the difference between forward spatter and backward spatter?

Forward spatter travels in the same direction as the impact force, while backward spatter moves towards the force. Signup and view all the answers

Match the following bloodstain terms with their definitions:

Static stains = Drip stains, pools of blood Active stains = Spatter, cast-off stains, arterial spurting Transfer stains = Wipes, swipes, pattern transfers Signup and view all the answers

What factors affect external bleeding after wounding?

Location of the wound, low pressure system, high pressure system, head wound. Signup and view all the answers

What is the amount of blood in a head wound?

Large amounts of blood, as the head is a highly vascular area. Signup and view all the answers

It is possible to always know the right answer in blood spatter analysis.

False Signup and view all the answers

Before attempting blood spatter analysis, what is needed?

All of the information, including the coroner's report. Signup and view all the answers

What does a compression transfer imply?

It occurs when a fabric laying in a pool of blood is stepped on, resulting in an impression transfer. Signup and view all the answers

What happens once a victim is placed into a body bag?

Blood flow will occur; any spatter patterns on clothes should be removed before moving the victim. Signup and view all the answers

A surface that is not smooth can _____ the shape of the stain.

distort. Signup and view all the answers

Is full reconstruction of a crime scene possible?

False Signup and view all the answers

How does blood dry?

Outside in. Signup and view all the answers

Study Notes

Bloodstain Patterns and Characteristics

Accompanying drop: By-product blood drop formed during main drop creation.
Altered stain: Bloodstain showing physical changes.
Angle of impact: Acute angle at which blood strikes a target.
Area of convergence: Point indicating location of blood source in two dimensions through stain intersection lines.
Area of origin: Three-dimensional location where blood spatter originated.

Blood Patterns and Movement

Backspatter pattern: Bloodstain pattern resulting from blood moving opposite to the applied force, often seen in entrance wounds.
Cast-off pattern: Blood droplets released from a moving object.
Drip pattern: Result from liquid blood dripping into another liquid.
Flow pattern: Movement of blood across a surface due to gravity or target movement.
Mist pattern: Blood reduced to micro-drops from high force, like a gunshot.

Bloodstain Analysis Terminology

Parent stain: Original bloodstain from which smaller satellite stains emanate.
Transfer stain: Bloodstain made when a blood-bearing surface contacts another surface.
Void: An absence of blood where a barrier was present.
Wipe pattern: Altered pattern caused by an object moving through a wet stain.

Factors Influencing Blood Loss and Patterns

Cessation cast-off pattern: Blood released during an object's rapid stop.
Influences on bleeding: Wound location and pressure systems (high = fast, low = slow).
Volume correlations: Head wounds produce large blood loss; surface wounds yield small amounts.

Spatter Types and Effects

Forward spatter vs. backward spatter: Forward travels in the wound’s direction; backward moves towards the impact source.
Size correlation: Higher force causes smaller blood drops, while lower force yields larger drops.
Frothy blood: Blood mixed with air, indicating lung or neck wounds.

Identification and Analysis Techniques

Angle of impact determination: Calculated using stain length and width, applying the inverse sine function.
Expiration patterns: Mimic spatter; less vivid and can have mucus strands.
Patterns tell directionality: Help identify minimum blows and origin position.

Scene Reconstruction and Reporting

Reconstructing crime scenes: Full reconstruction is often unfeasible; reports provide the most probable scenarios.
PBA documentation: Reports must include assumptions and limitations.
Coroner's report dependence: Essential for accurate blood spatter analysis.

Miscellaneous Facts

Human blood volume and distribution: Average is 4-6 liters; venous system holds 58%, arterial 13%, and heart 9%.
Surface interaction effects: Non-smooth surfaces distort bloodstains' appearance.
Pattern formation principles: Compression transfers occur when fabric contacts blood and leaves an impression.

Drying and Transfer Properties

Blood drying method: Blood dries from outside to inside.
Capillary action: Blood movement follows straight pressing and lifting techniques.
Repetitive transfers: Occur through object contact, which leads to repeated impressions.

Safety and Practical Concerns

Identifying pattern origins: Requires the actual object that caused the pattern for correlation.
Transfer patterns' safety: Avoid determining the source of transfer patterns due to potential contamination.
Secondary transfers: Result from underlying layers affecting primary impressions.

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Test your knowledge of key terms in advanced forensics with these flashcards. Each card features a specific term related to bloodstain analysis along with its definition. Perfect for students and professionals looking to reinforce their understanding of forensic science.