Module 7.1: Introduction to Criminalistics & Forensic Science

I. Defining the Terms

A. Forensic Science

Definition: Forensic Science is the application of a broad spectrum of sciences to answer legal questions. It is the all-encompassing field.
Scope: Includes fields like:
- Forensic Pathology: Determining the cause of death (autopsy).
- Forensic Anthropology: Identifying human remains.
- Forensic Entomology: Studying insects to determine time of death.
- Forensic Psychiatry: Assessing mental state in legal proceedings.
- Criminalistics.

B. Criminalistics

Definition: Criminalistics is the branch of forensic science that deals with the scientific analysis of physical evidence. It is often referred to as "crime laboratory science."
Focus: The core focus of the criminalist is to link a suspect to a crime scene or a victim through the analysis of physical evidence.
Analogy: If Forensic Science is a university, Criminalistics is the College of Natural Sciences within it.

Sa madaling salita, ang Criminalistics ay ang siyensya ng pag-aaral ng pisikal na ebidensya - yung mga bagay na makikita at mahawakan sa crime scene tulad ng fingerprints, dugo, bala, droga, at iba pa. Kung ang Forensic Science ay parang buong eskwelahan, ang Criminalistics ay parang isang department lang na nag-focus sa laboratory analysis ng mga ebidensya.

Board Exam Tip: All criminalists are forensic scientists, but not all forensic scientists are criminalists. A forensic pathologist is a forensic scientist, but they are not a criminalist because they study the body itself, not just the physical evidence found on it.

Para mas maintindihan: Lahat ng taga-criminalistics ay forensic scientist, pero hindi lahat ng forensic scientist ay taga-criminalistics. Halimbawa, yung forensic pathologist (yung nag-aautopsy) ay forensic scientist din, pero hindi siya criminalist kasi ang ginagawa niya ay pag-aralan yung katawan mismo, hindi yung mga ebidensyang natagpuan lang.

B. Testimonial vs. Physical Evidence

Feature	Testimonial Evidence (Witness Statement)	Physical Evidence
Nature	Subjective, based on human perception.	Objective, based on scientific analysis.
Reliability	Can be flawed due to memory lapses, bias, or outright lying.	Unbiased. "Evidence does not lie."
Impact	Can be very persuasive but is often questioned.	Can be very powerful and is difficult to refute.

IV. The Role of the Criminalist

A criminalist, also known as a forensic scientist or crime lab examiner, has several key roles:

Analyze Physical Evidence: Their primary job is to apply scientific principles and techniques to analyze evidence submitted to the laboratory.
Write Reports: They must prepare detailed, accurate, and objective reports on their findings. These reports become part of the official case file.
Provide Expert Testimony: A criminalist must be able to go to court and testify as an expert witness. They explain their scientific findings to the judge and jury in a clear and understandable way, and offer their expert opinion on the significance of the evidence.

The Forensic Triad

The work of the criminalist revolves around linking the three key elements of a crime:

The Crime Scene
The Suspect
The Victim

Physical evidence is the "glue" that connects these three components. For example, a suspect's fingerprint (physical evidence) found at the crime scene links the suspect to the scene. A victim's blood (physical evidence) found on a suspect's knife links the suspect to the victim.

Isipin mo ang Forensic Triad bilang tatlong bilog (circles): Crime Scene, Suspect, at Victim. Ang trabaho ng criminalist ay mag-hanap ng physical evidence na mag-connect ng tatlong ito. Halimbawa: Nakita ang fingerprint ng suspect sa crime scene - connected na! May dugo ng victim sa kutsilyo ng suspect - connected na ulit! Kaya ang physical evidence ang "glue" o pandikit ng tatlo.

Board Exam Tip: Memorize the Forensic Triad - Crime Scene, Suspect, Victim. Physical evidence links all three. This concept appears frequently in PRC exams!

V. Locard's Exchange Principle - The Foundation of Criminalistics

One of the most fundamental principles in criminalistics was established by Dr. Edmond Locard, a French criminologist often called the "Sherlock Holmes of France."

Locard's Exchange Principle States:

"Every contact leaves a trace."

This means that whenever two objects come into contact, there is always a transfer of material between them. When a person enters a crime scene, they will:

Leave something behind (e.g., fingerprints, hair, fibers from clothing, shoe prints, DNA)
Take something away (e.g., dust, fibers, blood, soil)

Why This Principle is Important:

No Perfect Crime: It is impossible to commit a crime without leaving any evidence. Even if the criminal is careful, microscopic traces will always be transferred.
Basis for Crime Scene Investigation: This principle is why crime scene investigators meticulously collect even the smallest pieces of evidence.
Cross-Transfer: Both the perpetrator and the crime scene/victim are "contaminated" by each other. This two-way exchange creates multiple opportunities to find evidence.

Examples of Locard's Principle in Action:

Burglary: A burglar breaks into a house. He leaves behind shoe prints, fingerprints on a window, and fibers from his jacket. He takes away dust from the house on his clothes and shoes.
Hit and Run: A car hits a pedestrian. Paint chips from the car are left on the victim's clothing. Blood and fibers from the victim are left on the car's bumper.
Homicide: The killer strangles the victim. The killer's skin cells (DNA) are found under the victim's fingernails. The victim's blood is found on the killer's shirt.

Sa madaling salita, ang Locard's Exchange Principle ay simpleng "every contact leaves a trace" - kapag may contact, may transfer. Walang perpektong krimen! Halimbawa: Pumasok ang magnanakaw sa bahay - may dadalhin siyang alikabok mula sa loob palabas, at may iiwan siyang fingerprints o damit fiber papasok. Parehong "contaminated" ang crime scene at yung suspect - ito ang tinatawag na cross-transfer. Kaya kahit gaano ka-ingat ang kriminal, may maiiwanan at madadala pa rin siyang ebidensya!

Board Exam Tip: Locard's Exchange Principle is one of the MOST tested concepts in Criminalistics. Remember: "Every contact leaves a trace" - cross-transfer always occurs. The principle explains WHY physical evidence is so powerful!

Mnemonic: LOCARD = Leave Or Carry Always Results in Detection

Introduction

Criminalistics is the heart of scientific crime investigation. It is the application of scientific techniques to the recognition, collection, identification, individualization, and interpretation of physical evidence. It is a branch under the broader umbrella of Forensic Science, which is the application of any science to the law. This module will define these key terms, establish the scope of criminalistics, and introduce the fundamental principles that guide the work of a forensic scientist.

Key Learning Objectives:

Differentiate between Criminalistics and Forensic Science.
Define "Physical Evidence" and explain its importance.
Understand the scope and various divisions of Criminalistics.
Explain the role of the criminalist in the justice system.
Introduce the concept of the "forensic triad."

II. The Importance of Physical Evidence

Definition: Physical Evidence refers to any tangible object or material that can be used to connect a suspect, victim, or a location to a crime. It is any object, big or small, that can establish that a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator.

Ang Physical Evidence ay kahit anong bagay na makikita at mahawakan na pwedeng mag-connect ng suspect, victim, o lugar sa isang krimen. Maliit man o malaki - basta tangible object na pwedeng patunayan na may krimen na nangyari o pwedeng mag-link ng suspect sa crime scene.

A. Why is Physical Evidence Important?

Proof of a Crime: It can prove that a crime actually occurred (e.g., a broken window, a spent cartridge case).
Linking a Suspect: It is the most reliable way to connect a suspect to a crime scene (e.g., fingerprints, DNA, fibers).
Corroborating Testimony: It can support or refute the statements of witnesses, victims, or suspects. A witness says the suspect wore a red shirt; a red fiber is found at the scene.
Identification: It can identify a person (fingerprints, DNA) or a substance (drug analysis).
Reconstruction of Events: The pattern and location of physical evidence can help investigators reconstruct the sequence of events at a crime scene.

B. Testimonial vs. Physical Evidence

| Feature | Testimonial Evidence (Witness Statement) | Physical Evidence |

III. The Scope and Divisions of Criminalistics

Criminalistics is divided into several specialized fields, each focusing on a different type of physical evidence. These divisions are typically found within a crime laboratory.

The Six Main Divisions of a Crime Laboratory:

Forensic Photography: The art and science of documenting the crime scene and evidence through photography. It provides a permanent, visual record.
Personal Identification: The most famous division, focused on identifying individuals.
- Dactyloscopy: Fingerprint identification.
- DNA Analysis: Genetic fingerprinting.
Questioned Documents Examination: The analysis of documents to determine authenticity, authorship, or to detect alterations. This includes handwriting analysis.
Forensic Ballistics: The science of firearms and ammunition. It involves identifying if a specific firearm was used to fire a bullet or cartridge case found at a crime scene.
Forensic Chemistry: The analysis of non-biological chemical substances.
- Drug identification.
- Arson investigation (identifying accelerants).
- Gunshot residue analysis.
Forensic Toxicology & Biology:
- Toxicology: The analysis of body fluids and tissues to detect the presence of drugs or poisons.
- Biology/Serology: The analysis of biological evidence like blood, semen, and saliva.

Conclusion

Criminalistics is the scientific backbone of the criminal investigation process. It transforms silent, inanimate objects—fingerprints, fibers, bullets, and bloodstains—into powerful testimony that can solve crimes and bring offenders to justice. By objectively analyzing physical evidence, the criminalist provides a crucial check on human error and bias, ensuring that the conclusions reached by the justice system are based on fact, not just speculation. Understanding the scope and principles of this field is the first step toward appreciating the power of science in the service of truth.