Fingerprints and DNA_2024_Student (3)

Fingerprints and DNA

Aims for the Lecture

  • Use of fingerprints in identification.

  • Procedures for fingerprint identification.

  • Introduction to IDENT 1 and the Criminal History System (CHS).

  • Fingerprinting practices for deceased individuals.

  • The significance of DNA and its specific sites on a body.

Fingerprints

Definition

  • Fingerprints are created through the transfer of sweat from the pores of fingers onto surfaces.

  • They serve as a record of the skin's pattern and unique physical characteristics.

  • Composed of a complex combination of ridges and furrows.

  • Develop early in life and persist until after death.

Types of Fingerprints

  • Latent: Invisible prints made by sweat and oils from fingers.

  • Patent: Visible prints left on surfaces from colored substances.

  • Plastic: Indented prints left in soft materials.

Anatomical Structure

  • Layers:

    • Epidermis: Outer layer of skin containing keratinized cells.

    • Dermis: Contains sweat glands and papillae.

    • Sweat Pores: Openings allowing sweat to exit the skin.

Fingerprint Patterns

  • Key features include enclosure, bifurcation, and ridge endings.

Fingerprinting Cadavers

Importance of Fingerprinting Cadavers

  • Crucial in identifying victims of murder or suspicious deaths to provide closure to families.

  • Essential in cases where traditional identification methods are not viable (e.g., fire, drowning).

  • Accurate fingerprint evidence is admissible in courts for establishing identity.

Types of Fingerprints Taken

  • Fingerprints: Critical for identification.

  • Plantar Impressions: May be taken from bare feet to aid in identification.

Identity Verification Processes

  • Searching local, national IDENT 1 databases and comparing with known records.

  • Validating against foreign collections through Interpol if applicable.

  • Using prints collected from the deceased's premises for comparison.

Mortuary Procedures

  • Conduct fingerprinting after the pathologist's examination.

  • Importance of health and safety during cadaver handling, including the necessity of suitable equipment.

  • Document visible patterns before fingerprinting begins.

  • Proper preservation of any removed body parts, requiring Coroner's permission.

Methods of Obtaining Fingerprints from Cadavers

Equipment Used

  • Photography for ridge detail documentation.

  • Use of ink, powder, tape, and cadaver spoons.

  • Double gloving for safety.

Techniques

  • Casting: Molding ridge details using malleable materials.

  • Powdering: Using appropriate powder based on skin condition.

Challenges in Fingerprinting Cadavers

Conditions Affecting Fingerprint Quality

  • Maceration: Skin wrinkling and possible detachment, requiring careful techniques.

  • Charring: Fire damage can make skin brittle; methods to restore pliability exist.

  • Decomposition: Difficult to manage due to skin condition; options include casting or photographing dermal ridges.

  • Mummification: Hard, creased skin can be challenging; techniques to soften tissue may be required.

  • Rigor Mortis: Stiffness of muscles must be managed delicately.

Identification Process in Bureau

Procedure at the Bureau

  • Identification takes precedence when cadaver prints are received.

  • A print from just one digit may suffice for identification, but having all ten is preferable.

Technology Used

  • IDENT 1 database for searching and matching fingerprint records.

  • Process involves scanning prints and identifying ridge characteristics.

DNA

Significance of DNA

  • Known as the "blueprint of life" containing hereditary information.

  • Composed of adenine, guanine, thymine, and cytosine.

  • Found as a double-stranded molecule held by hydrogen bonds.

Forensic Application

  • Used for identifying human remains, materials from crime scenes, and paternity testing.

  • Involves extraction and profiling of DNA from various biological materials.

Biological Materials for DNA

Crime Scene Samples

  • Common samples: blood, semen, hair, and other biological materials such as teeth and bones.

Reference Samples

  • Needed if no match is found, sourced from relatives or personal items.

  • Typical reference samples include buccal swabs or blood samples from family members.

DNA Database

Overview

  • National database allows search and match of DNA profiles.

  • Profiles can include police personnel and others identified in investigations.

Future Considerations

  • Advancements in technology expected for processing and analyzing DNA.

  • Ethical implications of expanding DNA databases and privacy concerns.

Summary of Techniques in Fingerprinting Cadavers

  1. Photography for detailed visualization.

  2. Inking of pliable fingers for impressions.

  3. Casting for capturing ridge patterns.

  4. Double Gloving to ensure contamination control.

  5. Moisture Management to dry digits thoroughly.

  6. Emergency Techniques for damaged skin conditions.