Mixed Deck — All ETC Topics Flashcards

Cyanoacrylate (superglue) fuming is primarily used to develop latent prints on which type of surface?

Answer: Non-porous surfaces such as plastic, glass, and metal

Cyanoacrylate fuming causes superglue vapors to polymerize on the amino acids, fatty acids, and proteins in latent print residue on non-porous surfaces.

Which packaging material is CONTRAINDICATED for storing arson evidence containing volatile accelerants?

Answer: Plastic bags

Plastic bags allow volatile accelerants to permeate through the bag walls, causing loss of evidence and potential cross-contamination.

When evidence is transferred between jurisdictions, what additional documentation is typically required?

Answer: Inter-agency transfer forms, official letters of authorization, and updated chain of custody entries

Inter-jurisdictional transfers require inter-agency transfer forms, authorization letters, and updated chain of custody entries to ensure legal continuity across different agencies.

When an evidence technician receives evidence from a first responder who did not properly package it, what should the technician do?

Answer: Accept the evidence, note the improper packaging in the chain of custody documentation, and repackage correctly

The technician should accept the evidence, thoroughly document the improper packaging as received, and then repackage it correctly, creating a transparent record of the packaging issue.

How should trace evidence such as loose fibers or hair be packaged at the crime scene to prevent loss?

Answer: In paper envelopes or using a druggist fold

Paper envelopes and druggist folds allow moisture to escape (preventing mold) while securely containing small loose particles without static buildup that plastic bags can cause.

Paint transfer evidence from a hit-and-run scene is best characterized using which combination of analytical methods?

Answer: FTIR spectroscopy and scanning electron microscopy with EDX (SEM-EDX)

FTIR identifies the organic binder and pigment chemistry of paint layers, while SEM-EDX provides elemental composition of inorganic pigments, together allowing detailed layer-by-layer comparisons.

When storing digital evidence such as a hard drive, which environmental factor is most critical to control?

Answer: Static electricity and magnetic fields

Static electricity and magnetic fields can corrupt or erase data on digital storage media, making anti-static packaging and shielded storage essential.

Which reagent is used as a presumptive test for blood that produces a luminescent reaction?

Answer: Luminol

Luminol reacts with the iron in hemoglobin to produce chemiluminescence, allowing detection of blood even when diluted or cleaned.

A crime scene contains a strong odor of accelerants. Before collecting accelerant samples, what safety precaution is most critical?

Answer: Ensure the area is ventilated and free of ignition sources

Accelerant vapors are flammable; the scene must be ventilated and all ignition sources removed before evidence collection begins.

Which powder is preferred for developing latent prints on dark, non-porous surfaces?

Answer: White or light-colored powder (e.g., titanium dioxide)

Light-colored powders provide the necessary contrast to visualize latent prints on dark non-porous surfaces.

Why is proper evidence storage crucial?

Answer: To protect integrity and admissibility

Proper evidence storage is crucial for protecting the physical and forensic integrity of items over time. Storing evidence in appropriate conditions (e.g., climate-controlled, secure) prevents degradation, contamination, or loss. This ensures its continued reliability and admissibility in court, maintaining its value throughout the legal process.

Why is it important to use a systematic search method?

Answer: To avoid missing evidence

Using a systematic search method, such as grid, spiral, or strip search, ensures that every area of the crime scene is thoroughly examined. This methodical approach minimizes the chance of overlooking crucial evidence, which might otherwise be missed during a haphazard or unorganized search. It provides comprehensive coverage and improves the likelihood of discovering all relevant items.

When collecting soil samples as comparison trace evidence, what is the correct procedure?

Answer: Collect samples from multiple locations including control areas away from the scene

Collecting samples from multiple locations — including known control areas — allows forensic geologists to compare the questioned soil to reference samples and assess significance.

Which of the following is NOT a valid method for collecting DNA evidence from a suspect's skin?

Answer: Rubbing a cotton swab over the back of the hand

A dry cotton swab rubbed over intact skin rarely collects enough epithelial cells for a reliable DNA profile, making it an unreliable collection method.

When submitting biological evidence to a forensic lab, which packaging material is preferred over plastic bags?

Answer: Paper bags or paper envelopes

Paper packaging allows moisture to escape, preventing mold and bacterial growth that would degrade DNA and other biological evidence.

What is the purpose of a 'north arrow' on a crime scene sketch?

Answer: To provide a consistent orientation reference for the sketch

A north arrow provides a standard directional reference so that the sketch can be accurately oriented relative to the physical world.

What is the primary reason evidence technicians should avoid eating, drinking, or smoking within the crime scene perimeter?

Answer: It can introduce foreign DNA, trace evidence, and contaminants that compromise the scene

Eating, drinking, or smoking within the perimeter risks depositing foreign DNA and trace materials that can mislead forensic analysis.

When seizing a smartphone as digital evidence, which data may be lost if the battery dies before forensic acquisition?

Answer: Volatile data in RAM such as active app states and temporary files

RAM is volatile memory that is erased when power is lost; active app states, decryption keys, and temporary data that could be forensically valuable are lost when the battery dies.

What does the term 'chain of custody' mean specifically in the context of digital evidence?

Answer: A documented record of every person who accessed or handled the digital evidence from collection through court presentation

Chain of custody for digital evidence tracks every person who handled or accessed the device or image, proving it has not been altered or tampered with.

What is the role of a forensic laboratory's evidence custodian?

Answer: To maintain chain of custody records and control access to submitted evidence

The lab evidence custodian is responsible for receiving, logging, storing, and tracking all submitted evidence to maintain an unbroken chain of custody.