Mixed Deck — All CSI Topics Flashcards

When photographing a footwear impression in mud, which sequence is correct?

Answer: Without scale first, then with scale, using oblique lighting for both

Best practice is to photograph first without a scale (to show the impression undisturbed), then with a scale, and use oblique lighting to reveal detail in both shots.

Under what circumstance may a CSI legally enter and process a crime scene without a search warrant?

Answer: When exigent circumstances exist, such as an ongoing threat to life

Exigent circumstances, such as a risk to life or imminent destruction of evidence, are recognized exceptions to the warrant requirement under the Fourth Amendment.

What is a 'rough sketch' in crime scene documentation?

Answer: A preliminary, not-to-scale drawing made at the scene for reference

A rough sketch is a preliminary, not-to-scale drawing created at the scene that will later be refined into a finished sketch.

What is the purpose of DNA analysis in forensic investigations?

Answer: To identify individuals through genetic material

DNA analysis is a powerful forensic tool used to create a unique genetic profile from biological samples like blood, saliva, hair, or skin cells. This profile can then be compared to known individuals or databases to identify suspects, victims, or establish connections between individuals and a crime scene. It provides highly reliable identification for investigations.

Why is it important to take photographs of the crime scene before collecting evidence?

Answer: To document evidence location and crime scene condition

Photographs provide a permanent visual record of the crime scene's original state before any evidence is moved or collected. They document the precise location of evidence, the overall layout, and the condition of the scene, which is crucial for reconstruction and later analysis. This initial documentation is vital for maintaining the context and integrity of the evidence.

Why is a crime scene sketch important?

Answer: To show spatial relationships of evidence

A crime scene sketch is crucial because it provides a scaled diagram illustrating the precise location of evidence relative to fixed points and other items within the scene. This visual representation helps investigators and jurors understand the layout and context of the evidence, which photographs alone cannot always convey accurately. It clarifies spatial relationships essential for reconstructing events.

What should be included in a crime scene investigator’s field notes?

Answer: Observations, evidence descriptions, and witness statements

Field notes are critical for documenting immediate observations, detailed descriptions of evidence, and initial witness statements at a crime scene. These notes serve as the primary, contemporaneous record of the investigation, ensuring accuracy and providing a foundational basis for official reports and court testimony. They capture raw, unfiltered information as it is discovered.

What forensic technique uses stable isotope ratios to determine geographic origin of materials?

Answer: Isotope ratio mass spectrometry (IRMS)

IRMS measures ratios of stable isotopes (like carbon-13/carbon-12) which vary geographically, linking materials to specific regions.

What does the term 'Level 3 detail' refer to in fingerprint examination?

Answer: Pore structure and edge morphology of individual ridges

Level 3 detail includes micro-features such as sweat pore positions and the precise shape of ridge edges, requiring high magnification.

What is the significance of 'substrate porosity' when selecting a latent print developer?

Answer: Porous surfaces absorb sweat components while non-porous surfaces retain them on top

Porous materials like paper absorb amino acids into the substrate, requiring chemical reagents, while non-porous surfaces hold deposits on top, suited for powders or CA fuming.

Which of the following best describes a 'transfer' bloodstain pattern?

Answer: A stain created when a bloody surface contacts another surface, depositing blood

A transfer pattern results from direct contact between a bloody surface (such as a hand or shoe) and another surface, producing a mirror image or partial impression.

What does the term 'fruit of the poisonous tree' refer to in the context of evidence law?

Answer: Evidence derived from an initial illegal search or seizure

The 'fruit of the poisonous tree' doctrine holds that evidence derived from an unconstitutional search is also inadmissible, not just the original illegally seized evidence.

An investigator discovers a faint, two-dimensional dusty footwear impression on a dark-colored tile floor. Which of the following collection methods would be most effective for recovering this type of evidence?

Answer: Electrostatic dust print lifter

An electrostatic dust print lifter is the most effective method for collecting dry or dusty residue impressions. It uses an electric charge to attract and bond the dust particles to a special lifting film, preserving the delicate details of the impression with minimal disturbance.

A CSI unit is reorganized so that latent print examiners, DNA analysts, and digital forensics staff all report to a single manager. This structure is known as:

Answer: A functional structure

A functional structure groups employees by specialty or function, such as forensic discipline, under a common manager.

Which insect is most commonly used in forensic entomology to estimate the minimum post-mortem interval (PMI)?

Answer: Calliphora vicina (blowfly)

Blowflies (Calliphoridae), particularly Calliphora vicina, are primary colonizers of remains and their developmental stages are used to estimate the minimum time since death.

When documenting bloodstain patterns, 'directionality' refers to:

Answer: The direction from which a blood drop traveled before impact, indicated by its shape

Directionality is determined by the elongated shape and satellite spatter of a bloodstain, with the pointed end indicating the direction of travel.

What is 'ridge dissociation' as observed in a latent print examination?

Answer: Breakdown or scattering of ridge structure due to pressure, disease, or damage

Ridge dissociation describes areas where ridges break apart or scatter, which can result from pressure distortion, skin conditions, or intentional alteration.

Which of the following is NOT a standard latent print pattern classification?

Answer: Spiral

The three standard Henry Classification pattern types are loops, whorls, and arches; 'spiral' is not a recognized classification category.

The phrase 'to a reasonable degree of scientific certainty' in expert testimony means:

Answer: The opinion is grounded in accepted methodology and reliable data

This legal phrase signals that the expert's opinion meets the threshold of scientific validity, not absolute certainty.

In a crime scene report, what is the purpose of an 'actions taken' section?

Answer: To document every investigative step performed at the scene, creating an auditable record

The 'actions taken' section creates a chronological, auditable record of every investigative action, demonstrating thoroughness and proper procedure.