ETC Cheat Sheet 2026

The 30 highest-yield ETC facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which storage environment is MOST appropriate for long-term preservation of latent fingerprint cards? → Cool, dry, dark environment
2. Which packaging material is CONTRAINDICATED for storing arson evidence containing volatile accelerants? → Plastic bags
3. Which type of evidence packaging is most appropriate for wet biological samples? → Paper bags or breathable containers to prevent mold growth
4. Why is scene documentation essential in crime scene processing? → To support evidence analysis and court testimony
5. What physical property of glass fragments is measured to help determine whether two samples share a common origin? → Refractive index
6. What is a minutiae point in fingerprint analysis? → A specific ridge characteristic such as a ridge ending or bifurcation used for comparison
7. Which body fluid is identified by the presence of p30 (PSA) protein confirmed by immunological testing? → Seminal fluid
8. Which federal law governs the interception of electronic communications and must be considered when collecting digital evidence? → Electronic Communications Privacy Act (ECPA) and the Wiretap Act
9. How should an evidence technician handle electronic devices found at a crime scene to preserve digital chain of custody? → Document their condition, place in Faraday bags, and record all handling
10. Which alternate light source wavelength range is commonly used to visualize fluorescent fingerprint powders? → Blue-green light (450–530 nm) with orange or yellow goggles
11. When evidence is sealed in a tamper-evident bag, what should be written or affixed on the outside of the bag? → Case number, date, item description, and initials of the collecting officer
12. When collecting soil samples as evidence, what is the recommended minimum number of samples to collect from a questioned area? → At least three samples from different areas of the questioned zone
13. What are the three fundamental fingerprint pattern types recognized in classification systems? → Loops, whorls, and arches
14. What is gunshot residue (GSR) primarily composed of, and why is it significant as trace evidence? → Lead, barium, and antimony particles unique to firearm discharge
15. Bloodstain pattern analysis (BPA) can help investigators determine which of the following? → The direction, speed, and origin of blood shed at the crime scene
16. Which factor determines whether evidence should be collected using a swab versus scraping? → Wet or moist stains are swabbed; dry stains on hard surfaces are scraped
17. Which powder is preferred for developing latent prints on dark, non-porous surfaces? → White or light-colored powder (e.g., titanium dioxide)
18. An evidence technician needs to collect a paint transfer from a hit-and-run vehicle. Which tool is most appropriate? → Clean scalpel or razor blade
19. Evidence technicians may be asked to obtain inked fingerprints from a deceased person. Which technique is used when skin is wrinkled or decomposed? → Tissue builder injection or rehydration using softening solutions prior to inking
20. Which action would MOST compromise the integrity of digital evidence found on a computer at a crime scene? → Powering on the computer to check its contents
21. A technician is casting a tire track in soft soil. Which material is most commonly used? → Dental stone (die stone)
22. A freeze-thaw cycle occurring in an improperly stored biological sample PRIMARILY causes: → Cell lysis and degradation of genetic material
23. Why is tamper-evident packaging used? → To prevent and detect tampering
24. Why should different types of evidence (e.g., firearms, chemicals, biologicals) be stored in separate areas of an evidence room? → To prevent cross-contamination and comply with safety regulations
25. At an outdoor homicide scene, what environmental factor poses the greatest threat to trace DNA evidence? → UV radiation and moisture
26. What should be worn when handling evidence to avoid contamination? → PPE such as gloves and masks
27. Which reagent is used as a presumptive test for blood that produces a luminescent reaction? → Luminol
28. What is the primary reason biological evidence such as blood swabs must be air-dried before packaging? → To prevent mold and bacterial degradation from moisture
29. Which hashing algorithm is most commonly used to verify the integrity of a digital evidence image? → MD5 or SHA-256
30. How many points of comparison are required by US federal standards to declare a fingerprint identification? → There is no mandated minimum — examiners use a holistic sufficiency standard