CLE Criminalistics: Forensic Foundations + Lab Techniques

CLE Criminalistics is the subject most reviewers underestimate. It looks technical, sounds intimidating, and yet the cle criminalistics paper is one of the most predictable on the entire board. Memorise the right facts, drill the right techniques, and you'll bank a high score from a subject that scares half the room.

The trick? Criminalistics is built on six well-defined sub-subjects. Each one has a small, finite set of facts the PRC Board for Criminology pulls from. We'll walk through all six.

The Six Sub-Subjects of Criminalistics

• Personal Identification — fingerprints, dactyloscopy, anthropometry. Around 20 items.
• Forensic Ballistics — firearms, ammunition, comparison microscopy. Around 20 items.
• Forensic Photography — crime scene photography, lighting, documentation. Around 10 items.
• Questioned Documents — handwriting, typewriting, ink and paper analysis, alterations. Around 15 items.
• Lie Detection / Polygraph — instruments, techniques, admissibility. Around 10 items.
• Forensic Chemistry and Toxicology — drug ID, blood, semen, hair, DNA basics. Around 25 items.

Personal Identification: The Fingerprint Block

Fingerprint items dominate this block. The PRC Board recycles three high-value frameworks every cycle:

• The three fingerprint patterns — Loop, Whorl, Arch. Then the subtypes (radial loop, ulnar loop, plain whorl, central pocket whorl, double loop whorl, accidental whorl).
• The Henry classification system — primary classification using digit numbers and a fixed ratio. Drill the formula.
• Ridge characteristics — ending ridge, bifurcation, dot, island, lake, spur, crossover. Identification minutiae.

Anthropometry

Bertillon's system. Largely obsolete in practice, but tested as an item asking for its inventor and the reason it fell out of use (the West/West case). Memorise the historical narrative.

Forensic Ballistics

This is the densest block. Three fields:

• Interior ballistics — what happens inside the firearm.
• Exterior ballistics — bullet flight from muzzle to target.
• Terminal ballistics — what happens at the target.

Add a fourth — forensic ballistics — which is the comparison and identification side. Test items focus heavily on rifling marks, cartridge case identification, and the direction of fire from spent shells.

Memorise These Three Numbers

The board loves numerical items in ballistics. Common returners: standard rifling twist rates, calibre conversions (.38 to 9mm), and bullet drop at standard ranges. Pick a textbook reference and stick to its numbers — different references give slightly different figures, and consistency wins.

Forensic Chemistry and Toxicology

This is the highest-yielding block. About 25 items per cycle, and most of them sit on a finite knowledge base:

• Drug identification colour tests — Marquis (positive purple-violet for opiates and amphetamines), Mecke, Mandelin, Duquenois-Levine (cannabis).
• Blood tests — Kastle-Meyer (presumptive), Takayama, Teichmann (confirmatory). Then ABO grouping basics.
• Semen tests — Florence (presumptive), Barberio (confirmatory), acid phosphatase.
• Toxicology — Reinsch test (heavy metals), Stas-Otto (alkaloids).

Questioned Documents and Polygraph

Questioned documents items hover around 15 per cycle. Drill: handwriting characteristics (line quality, slant, alignment, spacing), the difference between simulated and traced forgeries, and ink chronology techniques.

Polygraph items focus on the four channels — pneumograph (breathing), galvanograph (skin conductivity), cardiosphygmograph (cardiovascular), and sometimes a movement sensor. The Control Question Technique vs the Guilty Knowledge Test is a recurring contrast item.

How to Study Criminalistics

1. Week 1 — Personal identification. Memorise the patterns and ridge characteristics. Drill 50 items.
2. Week 2 — Ballistics. Build flashcards for calibres, rifling, and the three fields. Drill 50 items.
3. Week 3 — Forensic chemistry. This is the highest-yield block — give it the most time. Drill 80 items focused on drug colour tests and blood/semen tests.
4. Week 4 — Questioned documents, photography, polygraph. Light reading, heavy MCQ drilling. 60 items mixed.

Add a full-length 100-item Criminalistics mock at the end of week 4. Aim for 75% before moving on to the next subject.

Common Traps

• Presumptive vs confirmatory — examiners love framing items where the trap option swaps the two. Kastle-Meyer is presumptive. Teichmann is confirmatory.
• Forensic photographer's roles — the photographer doesn't sketch or collect. Distinct roles, distinct tools.
• Polygraph admissibility — generally not admissible without stipulation in Philippine courts. Items frame this as a scenario.

Forensic Photography: Beyond Equipment

The 10 photography items per cycle test concept and procedure, not gear. The bank pulls from a stable set:

Categories of Forensic Photography

• Crime scene photography — overall, mid-range, close-up.
• Surveillance photography — covert, telephoto, low-light.
• Mug shots — front and profile, standardised lighting.
• Evidence photography — with scale, identification placard, neutral background.
• Aerial photography — for large scenes, vehicular accidents at scale.

Technical Concepts to Memorise

• Aperture — controls depth of field. Smaller aperture (higher f-number) = deeper focus.
• Shutter speed — controls motion blur. Slower = more light, more blur.
• ISO — sensor sensitivity. Higher ISO = more grain.
• Depth of field — the range of focus. Critical for evidence photography.
• Exposure triangle — aperture, shutter speed, ISO interact.

Common Photography Items

Items frame scenarios: a low-light interior crime scene, a moving vehicle as a getaway, an evidence item that needs to fill the frame. Pick the camera setting framework that fits — wider aperture for low light, faster shutter for motion, macro for evidence close-ups.

Questioned Documents: The Examiner's Toolkit

QD items deliver 15 per cycle. The examiner's toolkit covers:

Handwriting Analysis

Twelve discriminating elements: line quality, line direction, slant, alignment to baseline, spacing, size, proportion, letter formation, connecting strokes, beginning and ending strokes, pen pressure, and individual habits. Items frame this as identification — match the questioned document to the standard.

Forgery Types

• Simulated forgery — copying from a model. Slow, deliberate strokes; signs of hesitation.
• Traced forgery — using carbon or backlit tracing. Indented lines visible.
• Free-hand simulation — practiced enough to flow. Hardest to detect.
• Genuine but slip-shod — actual signature but rushed. Not forgery.

Ink and Paper Analysis

• Ink chronology via solvent extraction or thin-layer chromatography.
• Paper analysis — fibre composition, watermark, age.
• Erasures — chemical, mechanical (rubber), physical (knife). Each leaves different signatures.

Polygraph: The Four Channels

The polygraph instrument records four physiological responses simultaneously.

• Pneumograph — respiratory rate via chest belts.
• Cardiosphygmograph — cardiovascular activity via blood pressure cuff.
• Galvanograph — electrodermal activity via finger sensors.
• Movement sensor — detects countermeasures.

Test Formats

• Control Question Test (CQT) — comparison between control and relevant questions.
• Guilty Knowledge Test (GKT) / Concealed Information Test (CIT) — tests for knowledge only the perpetrator would have.
• Relevant-Irrelevant Test (RIT) — older format, less common.

Admissibility

Polygraph results are generally inadmissible in Philippine courts without stipulation. The reliability has not been judicially accepted as scientifically valid. Items frame this as a scenario where the prosecution offers polygraph results — pick the rejection.

The Forensic Chemistry Memory Bank

This is the highest-yield single block in Criminalistics. Around 25 items. Build flashcards for these tests:

Drug Identification — Colour Tests

• Marquis test — purple/violet for opiates and amphetamines.
• Mecke reagent — blue-green for opiates.
• Mandelin reagent — orange/brown for many alkaloids.
• Duquenois-Levine — purple for cannabis.
• Dille-Koppanyi — violet for barbiturates.
• Cobalt thiocyanate — blue for cocaine.

Blood Tests

• Kastle-Meyer — presumptive (phenolphthalein, pink colour).
• Luminol — presumptive (chemiluminescence under UV).
• Takayama — confirmatory (haemochromogen crystals).
• Teichmann — confirmatory (haemin crystals).

Semen Tests

• Florence test — presumptive.
• Barberio test — confirmatory.
• Acid phosphatase — presumptive enzymatic.

Toxicology Tests

• Reinsch test — heavy metals (arsenic, mercury, antimony).
• Stas-Otto procedure — alkaloids extraction.

Personal Identification Beyond Fingerprints

• Bertillon's anthropometry — historical method, replaced by fingerprints after the West/West case.
• Forensic odontology — bite mark analysis, dental record matching for unidentified bodies.
• DNA profiling — STR (short tandem repeat) analysis is the current standard.
• Voice identification — spectrographic analysis. Limited admissibility.

How Super Tutor's CLE Track Helps

Our CLE Criminology track tags every Criminalistics item by sub-block — personal ID, ballistics, chem, documents, polygraph — so your weekly analytics report shows exactly where you're leaking points. Drill targeted blocks, not generic mixed sets. Focused Yearly is ₱1,999/year.

For the broader CLE strategy, see the Complete CLE Guide 2026 and the six-subject rotation. Verify the latest TOS at PRC's Criminology Board page.

FAQ

Is DNA tested heavily?

Light coverage — 3 to 5 items. Know the basics: STR analysis, mitochondrial vs nuclear DNA, and chain of custody for biological samples.

Do I need to memorise specific calibres and bullet weights?

Yes for common calibres — .22, .38, 9mm, .45, .357. Specific bullet weights only when comparing similar calibres (9mm vs .380).

Is forensic photography purely technical?

No. Items mix technique (lighting, focus, depth of field) with documentation rules (overall, mid-range, close-up shots, scale included).

Will the polygraph block carry many items?

Around 8–10. The instrument's four channels and the two main test formats are the high-yield items.

How accurate are the colour-test reagent associations?

The associations in the textbooks are stable. Practical lab work shows occasional false positives, but the test rewards the textbook association. Learn the textbook version cleanly first.

Is questioned documents worth deep study?

For a 15-item block, yes. Twelve discriminating elements plus the four forgery types covers most of it. Drill 50 items and you'll bank most of the points.

Next Steps

• Complete CLE Guide 2026
• CLE Six-Subject Rotation
• CLE Crime Detection & Investigation
• Super Tutor's CLE Track