Forensic Exam

What is forensic science?

The application of scientific knowledge and techniques to legal investigations, helping solve crimes, identify offenders and clear innocent people.

What is Locard’s Principle in relation to forensic science?

“Every contact leaves a trace”: when two objects or people touch, material can transfer between them, linking suspects, victims and crime scenes.

What is the role of a forensic scientist?

Collect and analyse scientific evidence, provide expert testimony, and train others in recognising, collecting and preserving physical evidence.

toxicology

Analyses blood and body tissues for drugs and poisons

entomology

Studies insects to help determine time of death.

pathology

Examines body tissues and performs autopsies to determine cause of death.

odontology

Examines teeth, dental records and dental work for identification.

anthropology

Investigates human remains; the slides specifically describe skeletal analysis under osteology.

botany

Analyses plant evidence.

chemistry

Analyses substances such as paint, glass, inks and chemical residues

dactylology (how & when are fingerprints formed & made)

Examines and compares fingerprints.

serology

analyses body fluids, such as blood.

radiology

works with x-rays

psychology

Helps investigate behaviour; the slides assign personality profiling from evidence to a psychiatrist.

different types of evidence

direct, circumstantial, trace, testimonial & transient

direct evidence

circumstantial evidence

trace evidence

testimonial evidence

role of eyewitness testimonials and the factors that might affect/influence them

Eyewitness accounts provide descriptions, help reconstruct events and give investigators leads, but should not be relied on alone.Forensics.pdf

Factors include age, memory, cross-race recognition, concentration, viewing time, position, lighting, drugs/alcohol, stress, distractions, disguises and personal prejudices; leading questions and information from others can also alter memories—the misinformation effect

processes involved in processing a crime scene

• Survey and protect: Check safety, identify boundaries and cordon off the scene.Forensics.pdf

• Interview: Ask witnesses or victims what allegedly happened.Forensics.pdf

• Examine: Locate evidence, entry/exit points and the scene’s layout.Forensics.pdf

• Photograph: Record overall views and individual evidence items.Forensics.pdf

• Sketch: Record the layout and exact positions of evidence.Forensics.pdf

• Process: Identify, collect, record and preserve evidence for laboratory analysis.

what is the bertillon system and its flaws

An early identification system using measurements of bony body parts, also called anthropometry.Forensics.pdf
Its flaw was that different people could have almost identical measurements and appearances, causing mistaken identification, as illustrated by Will West and William West.

what is an identikit/facial composite and its limitations when using them

An image constructed by combining facial features from a witness’s description, using drawings, an artist or software.Forensics.pdf
Accuracy depends on the witness’s memory; remembering separate features is difficult, and constructing a composite may interfere with later identification.Forensics.pdf

what is biometrics and how is it more frequently being used in forensic investigations

Measurable biological, physical or behavioural characteristics used to identify people—for example, DNA, fingerprints, facial features, iris patterns, voice and gait.Forensics.pdf
Computer systems capture these characteristics and compare them with stored records, increasingly supporting identification and security.

3 fundamental principles of fingerprints

• Individuality: No two people have been found with exactly the same fingerprints.Forensics.pdf

• Permanence: Fingerprint patterns remain unchanged throughout life.Forensics.pdf

• Classification: Fingerprints have recognisable general ridge patterns.

how & when do fingerprints form

Friction ridges develop during the fourth to fifth month of embryonic development; genetics influences the overall pattern, while fine details vary.Forensics.pdf
Touching a surface can leave a ridge impression through deposits of perspiration, oils, bacteria and dead skin.

what are the different types of fingerprints

arches, loops, whorls and composites

what are fingerprints used for in forensic science (latent prints?)

Crime-scene prints are photographed and compared with known prints, including through AFIS—Automated Fingerprint Identification System.Forensics.pdf

• Powder: Adheres to moisture/oily deposits; the developed print can be lifted with tape onto a card.Forensics.pdf

• Ninhydrin: Reacts with amino acids, producing purple prints.Forensics.pdf

• Iodine fumes: Produce temporary yellow-brown prints through interaction with fats/oils.Forensics.pdf

• Cyanoacrylate fumes: The “superglue method” produces an off-white print.Forensics.pdf

The slides distinguish visible prints, impressions in soft material, and latent prints, which need development to become visible.

how many teeth should human have?

32

what can dental records reveal? when might they be used?

Dental records and dental work can help identify human remains; the slides also describe comparing dental patterns with bite impressions and collecting saliva from bite sites for DNA.Forensics.pdf
The number of adult/child teeth is not stated in the provided slides.

list the different types of trace fibre & the origins of each. how can they be determined or assist in a forensic investigation?

label this diagram (structure of hair)

• Cuticle: Outer layer of overlapping scales.Forensics.pdf

• Cortex: Protein-rich layer surrounding the medulla; contains pigment.Forensics.pdf

• Medulla: Central core, which may be continuous, broken or absent.Forensics.pdf

• Follicle: Structure within the skin that produces the hair.

how and what imprints can be made using plaster castes

The slides mention photographing and casting tyre impressions, but do not explain a plaster-casting procedure.

what does a forensic chemist do?

Uses chemical techniques to identify and measure known or unknown substances and investigate their origins—for example, inks, dyes, paint, glass, soil, gunshot residue, explosives and accelerants.

distinguish the difference between solute, solvent & solution

• Solute: Substance being dissolved.Forensics.pdf

• Solvent: Substance doing the dissolving.Forensics.pdf

• Solution: Mixture formed when a solute dissolves in a solvent—for example, salt dissolved in water.

what is chromatography? whats its role in the separation of mixtures such as inks and dyes?

A method of physically separating a mixture because its components move at different rates through a medium.

How does chromatography separate inks/dyes?

A solvent carries the mixture through a stationary material; differences in solubility and attraction to the stationary phase make components travel different distances, producing separate colours or spots.Forensics.pdf
The resulting patterns can be compared with known ink or dye samples

what is the mobile phase and stationary phase in chromotography

• Mobile phase: Moving gas or liquid solvent that carries the mixture.Forensics.pdf

• Stationary phase: Material that stays in place and interacts with the components, affecting how quickly they move through it.Forensics.pdf

what is the rf factor formula?

Rf=distance travelled by solute / distance travelled by solvent front​

what is the use of dna and dna profiling? how does it help with forensic investigations

what does DNA stand for? where is it found?

deoxyribose nucleic acid and codes for proteins

•  found on linear chromosomes in a Eukaryotic cell nucleus

what is dna made up of?

DNA is made up of a nucleotide subunit: phosphate, deoxyribose sugar and N-containing bases – adenine, guanine, cytosine & thymine (pyrimidines and purines)

label (dna nucleotide & helix model)

what are the dna complementary base paring rules?

• now DNA complementary purine-pyrimidine base pairing rules between adenine-thymine and guanin-cytosine

what part of the body are dna samples often collected from

(hair follicles, swabbing the inside of the cheek – cells….)

phenotype

how the genotype is expressed or seen

genotype

combination of alles

allele

different forms of genes

explain the relationship between antigens on bloodcells and antibodies in plasma

which blood type is a universal donor and which is a universal recipient? why?

how are blood types deterimed using antigens and antisera?

what does rf factor mean and what implications does it have on pregancy?

• Rh factor - Rh + means the D antigens are present, Rh - means the D antigens are absent.

role of luminol in detecting unseen blood samples

what can blood splatters tell a forensic scientist?

Speed of flow, angle of impact or droplet, splatter zone, void area, whether the victim/suspect was moving or being dragged, smears