Physical Evidence in Criminal Investigations: Key Concepts and Case Studies

A set of Question-and-Answer flashcards covering key concepts, definitions, and case studies from the Physical Evidence lecture notes.

Physical Evidence

Tangible object, crime connection, legal proceeding, establish facts.

Main purposes of physical evidence

Support/contradict testimony, identify persons, establish crime elements, crime reconstruction.

Scope of physical evidence

Microscopic fiber to large weapon, collectable, preservable, scientifically examinable object.

Physical evidence admissible in court

Proper collection/preservation/documentation, material/relevant/competent, chain of custody.

Physical evidence importance in criminal investigations

Objective, reliable, links individuals, supports/refutes testimonies.

Physical evidence for crime scene reconstruction

Sequence of events, entry/exit, weapon via trace/ballistic/impression evidence.

Ivler road rage case evidence types

Physical, scientific, digital.

Ivler case outcome

Conviction for murder.

Ballistics contribution to Ivler case

Firearm matched bullet, gunshot residue, forensic comparisons linked weapon to murder.

Eyewitness testimonies role in Ivler

Witnesses placed Ivler at scene, descriptions matched photos.

Chain of custody

Unbroken, documented trail: collection -> storage -> lab; essential for admissibility.

People v. Dahil evidence outcome

Acquittal; broken chain of custody, no forensic chemist testimony; four-link chain unproven.

Four links of chain of custody

Seizure/marking, turnover to investigator, delivery to forensic chemist, submission to court.

Physical evidence classification by physical nature

Microscopic (dust, hair), solid (weapons, bullets), liquid (blood, urine), gaseous (fumes).

Physical evidence classification by examination type

Drug test, ballistics test, paraffin test, DNA profiling, handwriting analysis.

Biological evidence examples

DNA, hair, skin, tissues, nails, bones, teeth.

Analyzable body fluid examples

Saliva, blood, sweat, semen, urine.

Impression evidence

Tool marks, bite marks, shoe prints, tire tracks, fingerprints; match suspects.

Weapons and residues

Firearms, knives, explosive chemical residue; ballistics/chemical composition analysis.

Questioned documents

Forged documents, counterfeit money, handwriting, ransom notes; ink, handwriting patterns, printing methods examined.

Miscellaneous trace evidence

Fibers, dust, dirt, paint, glass, soil, metal, ashes; often unknowingly transferred.

Trace evidence locations

Victims, suspects, clothing, tools, vehicles, crime scenes; collected with specialized tools.

Trace evidence forensic analysis

Microscopy, spectroscopy (FTIR, SEM-EDX), DNA extraction.

Proper packaging importance

Prevents contamination/loss/degradation; preserves integrity/chain of custody.

Packaging materials: hair, fibers, dry samples

Paper envelopes/bags.

Packaging materials: dry non-biological items

Plastic containers.

Packaging materials: volatile liquids

Glass vials.

Packaging materials: trace evidence

Sealable tubes/bags.

Avoid plastic for moist/wet evidence

Risk of mold/bacterial degradation; air-dry first, then paper packaging.

Required labeling information on packages

Case number, item description, date/time, collector's name/signature, recovery location, tamper-evident seal.

Common packaging mistakes to avoid

Mixing sources, inadequate sealing, missing labels/details, improper materials.

Guiding principles for evidence collection

Sufficiency of sample, comparison standard, preserve individuality, proper labeling/sealing.

Preserving individuality in packaging

Package each specimen separately (avoid cross-contamination), label each item.

Chain of custody purpose in admissibility

Unbroken trail (collection to lab) to prevent tampering.

Scientific evidence

Requires scientific knowledge for understanding/analysis; admissible if it determines truth (Rule 128).

Vizconde Massacre case (1991)

Estrellita and daughters murdered; Carmela raped; forced entry; chain of custody issues; missing evidence, no DNA testing.

Vizconde: key evidence involved & missing

Involved: Blood, semen, bed sheets, clothing, knife wounds. Missing: Rape kit, semen samples, no DNA.

Vizconde case outcome (2010)

Supreme Court reversal, Webb acquitted; lack of credible forensic evidence, unreliable witness.

Vizconde case takeaways

Critical evidence handling/chain of custody; lost forensic material derails prosecution; science + procedure = admissibility.

Direct, circumstantial, and hearsay evidence

Direct: perceived by senses (eyewitness); Circumstantial: indirect, infers; Hearsay: others' statements, generally inadmissible (exceptions apply).

Forms of scientific evidence

Real/autoptic, Testimonial, Documentary.

Documentary evidence examples

Lab reports, expert affidavits, certificates, findings.