Criminology Chapter 16

Criminal Investigation

• Criminal investigation is a broad term that encompasses various specialties to determine how events unfolded during a criminal incident and establish an evidence-based fact pattern to prove guilt or innocence.
• The process becomes more complex when the criminal event is discovered after the fact or when the perpetrator is not clearly identifiable.

Sources of Information

• Objective Information (indirect): factual proof, including tangible objects presented to a court to prove or disprove a fact, e.g., weapons, fingerprints, fibres, hair, bodily fluids, and digital evidence.
• Subjective Information (direct): evidence offered by people directly or indirectly involved in the crime, based on their sensory perceptions.

Forensic Criminalistics

• Revolves around expert and highly specialized laboratory examinations conducted by physicists, chemists, pharmacologists, odontologists, and others.
• Combines two sub-systems: forensic tactics and forensic techniques.
• Forensic tactics involve the systematic study of criminal methods and techniques used to solve crimes.
• Forensic techniques involve analytical methods and modern technological aids to examine physical clues.

Forensic Science Services

• Physical Units: examine physical evidence, such as drugs, glass, paint, explosives, and soil.
• Biology Units: identify and individualize human body fluids, such as blood, semen, sweat, and saliva.
• Trichology (Forensic Analysis of Hair): compares hair samples to determine human or animal origin, species, racial/ethnic origin, male or female, and age.
• Ballistic Units: examine firearms, discharged bullets, cartridge cases, and shotgun shells.
• Disputed Document Units: examine handwriting and typewriting on questioned documents.
• Toxicology Units: analyze body fluids and organs to identify substances and poisons.
• Latent Fingerprint Units: detect, process, and examine latent fingerprints.

Crime Scene Investigation

• The crime scene is the area where an unlawful act was committed, and direct and indirect evidence can be found.
• Crime scenes can be indoors or outdoors, expansive or small, and may include vehicles.
• Scenes can be classified as primary, secondary, organized, disorganized, or mixed.
• Processing the crime scene involves securing and isolating the scene, recording the scene, conducting a systematic search, collecting and packaging physical evidence, and maintaining continuity of possession.

Processing the Crime Scene

• Securing the crime scene: stop all activities, remove people, and establish a perimeter.
• Recording the scene: uses photography, video recording, audio recording, sketching, and notes.
• Conducting a systematic search: involves observing and describing the scene, and searching for physical evidence.
• Collecting and packaging physical evidence: ensures evidence is handled and preserved to prevent contamination.
• Maintaining continuity of possession: accounts for everyone who handles the evidence, from collection to presentation in court.