Crime Detection
"Investigation time! Sherlock Holmes ang peg natin. Para maging mahusay na investigator, kailangan mong master ang techniques ng crime detection - from gathering evidence to solving cases!"
1. The Three I's of Investigation 🔍
Ito ang foundation ng criminal investigation - tatlong pillars para sa successful case!
📋 INFORMATION
Data gathered through inquiries
- • Witness interviews
- • Records/documents
- • Open sources (OSINT)
- • Background checks
- • Confidential informants
❓ INTERROGATION
Skillful questioning of persons
- • Suspects
- • Hostile witnesses
- • Reluctant witnesses
- • Uses psychology
- • Miranda Rights apply
🔬 INSTRUMENTATION
Scientific application
- • Forensic science
- • DNA analysis
- • Fingerprinting
- • Ballistics
- • Digital forensics
💡 Interview vs Interrogation
| INTERVIEW | Non-accusatory; for witnesses/victims; getting facts |
| INTERROGATION | Accusatory; for suspects; obtaining confession/admission |
2. Corpus Delicti (Body of the Crime) ☠️
Hindi ito literal na "dead body"! Corpus Delicti means the PROOF that a crime was actually committed.
🔍 Two Elements of Corpus Delicti:
1. PROOF OF INJURY/LOSS
Evidence that harm/damage occurred
- • Death in homicide cases
- • Missing property in theft
- • Injury in assault cases
2. CRIMINAL AGENCY
Evidence that the loss was caused by criminal act (not accident)
- • Manner of death (homicide vs natural)
- • Signs of forced entry
- • Evidence of intent
⚠️ Important: Confession alone is NOT enough! Must prove corpus delicti independently. A confession without proof that a crime occurred is insufficient for conviction.
3. Modus Operandi (Method of Operation) 🎭
Every criminal has their "signature style" - understanding M.O. helps solve serial crimes!
📊 Components of Modus Operandi:
| Factor | Description | Example |
|---|---|---|
| Time of Operation | When crime is committed | Always at night, between 12-3 AM |
| Target Selection | Type of victim/property | Only targets elderly living alone |
| Means of Entry | How access is gained | Always enters through back window |
| Instruments Used | Tools/weapons | Uses crowbar for forced entry |
| Method of Escape | How perpetrator leaves | Uses motorcycle, always heads north |
🎯 Modus Operandi vs Signature
M.O.: Behaviors NECESSARY to commit the crime (can change)
Signature: Unique behaviors NOT necessary but done anyway (stays constant)
📝 Importance of M.O.
- • Links related crimes
- • Narrows down suspects
- • Predicts future behavior
- • Criminal profiling
4. Crime Scene Investigation (CSI) 🔎
The crime scene is sacred! Proper handling ng evidence is critical for successful prosecution.
📋 Steps in Crime Scene Investigation:
SECURE AND PROTECT
Establish perimeter, use crime scene tape, control access
PRELIMINARY SURVEY
Initial walk-through, note boundaries, develop strategy
DOCUMENT THE SCENE
Photography, sketches, notes, videography
SEARCH FOR EVIDENCE
Use systematic search patterns (spiral, grid, strip)
COLLECT AND PRESERVE
Proper packaging, chain of custody, transport to lab
FINAL SURVEY AND RELEASE
Double-check, ensure all evidence collected, release scene
🔄 Crime Scene Search Patterns
SPIRAL
Indoor/small areas
GRID
Large outdoor areas
STRIP/LINE
Highway/long areas
WHEEL
Small, circular scenes
5. Chain of Custody ⛓️
Ang Chain of Custody ang nagpapatunay na AUTHENTIC ang evidence! Walang tampering!
⚠️ Definition:
Chain of Custody = Chronological documentation showing the seizure, custody, control, transfer, analysis, and disposition of physical evidence.
📊 Elements of Chain of Custody:
| Element | Must Document |
|---|---|
| MARKING | Unique identifier placed immediately upon collection |
| WHO | Names of all persons who handled the evidence |
| WHEN | Date and time of each transfer |
| WHERE | Location of evidence at each stage |
| WHY | Purpose of transfer (analysis, storage, court) |
| CONDITION | State of evidence at each transfer |
💡 Why Chain of Custody Matters: If broken, evidence becomes INADMISSIBLE in court! Defense lawyers will attack any gaps in the chain to exclude crucial evidence.
6. Types of Evidence 📦
🔍 PHYSICAL/REAL EVIDENCE
Tangible objects presented in court
- • Murder weapon
- • Bloodstains
- • Fingerprints
- • DNA samples
- • Drugs seized
💬 TESTIMONIAL EVIDENCE
Oral testimony under oath
- • Eyewitness accounts
- • Expert testimony
- • Character witnesses
- • Confessions
📄 DOCUMENTARY EVIDENCE
Written documents
- • Contracts
- • Letters/threats
- • Bank records
- • Digital files
🔗 CIRCUMSTANTIAL EVIDENCE
Indirect evidence requiring inference
- • Motive
- • Opportunity
- • Flight from scene
- • Behavior changes
⚖️ Direct vs Circumstantial Evidence
Direct: Proves fact directly (eyewitness saw killing)
Circumstantial: Requires inference (blood on clothes + motive + opportunity)
Note: Conviction can be based on circumstantial evidence alone IF unbroken chain of circumstances leading to conclusion of guilt.
7. Surveillance Techniques 👁️
📊 Types of Surveillance:
| Type | Description | Methods |
|---|---|---|
| CASING | Observation of places | Stakeout, reconnaissance |
| TAILING/SHADOWING | Following a person | Foot, vehicle, combination |
| ELECTRONIC | Technical surveillance | CCTV, wiretap (with warrant), GPS |
| UNDERCOVER | Infiltration operations | Buy-bust, entrapment |
✅ Entrapment (Legal)
Criminal intent ORIGINATES from the accused. Police merely provides opportunity.
❌ Instigation (Illegal)
Police INDUCES person to commit crime they wouldn't otherwise commit. ABSOLUTORY CAUSE!
📝 Practice Questions
1. What are the Three I's of Investigation?
Show Answer
Information, Interrogation, and Instrumentation. Information = data from inquiries; Interrogation = questioning suspects; Instrumentation = scientific/forensic application.
2. A suspects confession alone, without other evidence of the crime, is sufficient for conviction. True or False?
Show Answer
FALSE. Corpus delicti must be proven independently. Confession alone without proof that the crime actually occurred (injury + criminal agency) is insufficient for conviction.
3. Police officers pose as drug buyers to catch a known pusher. When the pusher sells drugs, is this entrapment or instigation?
Show Answer
ENTRAPMENT (Legal). The criminal intent originated from the pusher who was already engaged in drug selling. Police merely provided the opportunity to catch him in the act.
4. Which crime scene search pattern is best for a large open field?
Show Answer
GRID PATTERN. The grid/quadrant method is most effective for large outdoor areas as it allows systematic coverage of the entire area.
🎯 Exam Strategy Tips
📚 High-Yield Topics:
- ✓ Three I's of Investigation
- ✓ Corpus Delicti elements
- ✓ Chain of Custody requirements
- ✓ Crime Scene Investigation steps
- ✓ Entrapment vs Instigation
💡 Memory Tips:
- ✓ "III" = Information, Interrogation, Instrumentation
- ✓ "CORPUS" = Crime Occurred, Real Proof Undeniable Shows
- ✓ Entrapment = E for "Existing" intent
- ✓ Instigation = I for "Induced" by police
Test Your Knowledge! 🧠
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