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. Why is scene documentation essential in crime scene processing? → To support evidence analysis and court testimony
2. What physical property of glass fragments is measured to help determine whether two samples share a common origin? → Refractive index
3. What is a minutiae point in fingerprint analysis? → A specific ridge characteristic such as a ridge ending or bifurcation used for comparison
4. Which body fluid is identified by the presence of p30 (PSA) protein confirmed by immunological testing? → Seminal fluid
5. 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
6. 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
7. What are the three fundamental fingerprint pattern types recognized in classification systems? → Loops, whorls, and arches
8. 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
9. Bloodstain pattern analysis (BPA) can help investigators determine which of the following? → The direction, speed, and origin of blood shed at the crime scene
10. Which powder is preferred for developing latent prints on dark, non-porous surfaces? → White or light-colored powder (e.g., titanium dioxide)
11. 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
12. Why is tamper-evident packaging used? → To prevent and detect tampering
13. What should be worn when handling evidence to avoid contamination? → PPE such as gloves and masks
14. Which reagent is used as a presumptive test for blood that produces a luminescent reaction? → Luminol
15. Which hashing algorithm is most commonly used to verify the integrity of a digital evidence image? → MD5 or SHA-256
16. 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
17. Which condition is most likely to degrade DNA quality in biological evidence collected from an outdoor crime scene? → Prolonged exposure to UV light, heat, and humidity
18. An evidence technician submits a white powder to the lab. Which presumptive test would indicate the possible presence of cocaine? → Scott test (cobalt thiocyanate)
19. Forensic DNA analysis uses STR (Short Tandem Repeat) profiling. How many STR loci does CODIS analyze? → 20 core loci
20. What laboratory accreditation standard do most US forensic labs seek to ensure quality and competency? → ASCLD/LAB or ISO/IEC 17025 accreditation
21. What is the primary purpose of documentation in evidence handling? → To maintain integrity and legal validity
22. What type of bloodstain results from blood dripping into existing blood at a lower velocity? → Satellite spatter pattern with secondary droplets around the primary stain
23. What is a best practice for preserving digital evidence? → Use write-protected media and restrict access
24. In trace evidence searches, which area of the crime scene should generally be examined first? → The most volatile area likely to be disturbed or where evidence could be lost
25. What is the first step when collecting physical evidence at a crime scene? → Photograph and document it in place
26. What should an evidence technician do if they are asked a question in court that they do not know the answer to? → Honestly state 'I don't know' rather than speculating or guessing
27. When submitting biological evidence to a forensic lab, which packaging material is preferred over plastic bags? → Paper bags or paper envelopes
28. When should documentation begin for a piece of evidence? → Immediately upon discovery
29. Which of the following is a critical component of long-term evidence preservation? → Climate control and auditing
30. What must be recorded on a chain of custody form? → Details of every transfer of evidence