Forensics Chapter 2

First use of a robot armed with explosives by U.S. police

Dallas Police Department, July 7, 2016, to kill suspect Micah Xavier Johnson

5 Dallas Police Officers Killed – July 7, 2016

Ambush during protest; led to robotic explosive deployment

Micah Xavier Johnson

Suspect in Dallas police ambush

Dallas Police Officer J.D. Tippit

Murdered by Lee Harvey Oswald on Nov 22, 1963

Lee Harvey Oswald

Suspect in JFK assassination; killed Officer Tippit same day

Tunnel Vision & JFK Investigation

Warren Commission criticized for focusing too narrowly on Oswald

Amanda Knox Case (Opening Vignette)

Example of flawed investigation and contamination of evidence

Meredith Kercher

Murder victim in Italy (2007)

Raffaele Sollecito & Rudy Guede

Co-accused; Guede convicted, others acquitted

Aiden Fucci & Tristyn Bailey

Florida murder case highlighting digital evidence & procedure

Crystal Smith

Involved party in Bailey case

Tyre Nichols (Jan 7, 2023)

Died after police beating by Memphis SCORPION unit

George Floyd (May 25, 2020)

Death in police custody; changed policing & evidence documentation

Memphis Police “SCORPION Unit”

Disbanded after Nichols case

Kiki Camarena (DEA Agent)

Murdered in Mexico; led to Operation Leyenda

Operation Leyenda

Largest homicide investigation in DEA history

Emma Modesta Coronel Aispuro

Wife of Joaquín “El Chapo” Guzmán

Ovidio Guzmán López

Son of El Chapo; Mexican cartel leader

Overall Goal of a Criminal Investigation

Answer Who, What, When, Where, Why, How

Successful Criminal Investigation Is One In Which…

The truth is determined, evidence preserved, and justice served

Ensuring Crime Scene Safety

First priority: officer safety, medical aid, suspect control

First Responding Officer Responsibilities

Secure scene, render aid, detain suspects, preserve evidence

Importance of Securing the Scene

Prevents contamination, loss, or destruction of evidence

Chain of Custody

Documentation tracking evidence from collection to court

DA Form 4137

U.S. Army Chain of Custody document

4th Amendment

Protects against unreasonable searches and seizures

Search Warrants

Judicial authorization to search specific areas/items

Michigan v. Tyler (1978)

Fire scenes require warrants after emergency ends

Mincey v. Arizona (1978)

No “crime scene exception” to warrant requirement

Fruits of the Poisonous Tree

Illegally obtained evidence is inadmissible

Two Warrantless Search Examples

Exigent circumstances; consent searches

Custodial Interrogation

Questioning after arrest or deprivation of freedom

Miranda Rights (5)

Remain silent; statements used against you; attorney; appointed attorney; understanding

Physical Evidence Types

Objects, body materials, impressions

Packaging Evidence

Separate, breathable containers; prevent contamination

Druggist Fold

Paper fold used for trace evidence

When to Use Biohazard Stickers

Biological hazards (blood, bodily fluids)

What Can Happen with Improper Evidence Management

Contamination, loss, inadmissibility, wrongful convictions

Standard / Reference Samples

Known samples used for comparison

Obtaining Reference Samples

Buccal swabs, control materials

Buccal Swab

DNA sample from inside cheek

Substrate Controls (Arson)

Unburned material for comparison

Accelerant Detection Canines (ADCs)

Trained dogs to locate ignitable liquids

DNA Profiling

Identifies individuals using biological evidence

SANE Nurses

Specially trained forensic nurses in sexual assault cases

Destroyed Rape Kits – Fayetteville, NC

333 kits destroyed; massive investigative failure

CNN Report (Dec 4, 2018)

Springfield, MO mishandled rape investigations

Four Required Photo Types

Overall, mid-range, close-up, close-up with scale

Purpose of Crime Scene Photos

Permanently document the scene as found

Markers / Scales

Show size and location of evidence

Visual Tag

Identifies evidence location without touching it

DSLR Camera

High-quality digital photography

First Digital Camera (1989)

Dycam Model 1

Pixels / Resolution / Megapixels

Determines image clarity and detail

Videotaping Advantages

Continuous view; captures context

Videotaping Disadvantages

Missed details; motion blur

Trap Photography

Hidden cameras activated by movement

3-D Photography & 30% Overlap

Enables reconstruction and depth

Stitching

Combining multiple images into one panoramic view

Immersive Imaging / Virtual Tour

Interactive digital crime scene walkthrough

Leica C10 Scanner

Tripod-mounted 3-D laser scanner

Delta Sphere 3000

360° crime scene camera system

Photogrammetry

Measurements from photographs

Pictometry

Orthogonal (straight down) vs Oblique (angled) images

Aerial Photography

Drones, helicopters, overhead mapping

Initial Sketch

Rough, not to scale

Finished Scale Drawing

Accurate, measured, court-ready

North Arrow Importance

Shows orientation

Five Search Patterns

Line, grid, spiral, zone, wheel

CAD (Computer Aided Design)

Accurate digital mapping

Five Benefits of CAD

Accuracy, clarity, storage, sharing, scalability

CAD Origins

1957, Dr. Patrick J. Hanratty

Police Vehicle Searches & K-9s

Probable cause allows sniff searches

Night Vision Goggles (NVG)

Low-light operations

Body-Worn Cameras (BWC)

Accountability, evidence, transparency

Police Mobile Crime Scene Vans

On-site forensic processing

Facial Recognition (TSA)

Identity verification technology

Laptop Lineups (Thinkstream)

Digital suspect identification

PRONTO

Police rapid evidence management system

Direct vs Indirect Evidence

Direct proves fact; indirect implies fact

Modus Operandi (MO)

Criminal’s method of operation

Copycat Offenders

Crimes inspired by prior cases/media

Forensic Evidence Never Lies

Interpretation can be flawed, evidence itself is objective

Packaging Evidence by Police

Must prevent contamination and degradation