Trace Evidence II - Forensic Analysis Overview

Overview of Trace Evidence

• Major types of trace evidence:
  • Hair
  • Fiber
  • Paint
  • Glass
  • Soil

Hair & Mitochondrial DNA

• Mitochondrial DNA (mtDNA) can be extracted from the hair shaft.
• mtDNA is located in the mitochondria (cytoplasm) and is inherited maternally.
• All positive hair comparisons must be confirmed with DNA analysis.
• Nuclear DNA analysis provides individualization; mtDNA does not.

The Story of Anastasia Romanov

• 1917: February Revolution forces Tsar Nicholas II to abdicate.
• Nicholas, Alexandra, their four daughters, and one son captured post-October Revolution.
• Civil war in 1918 leads local authorities to order execution due to rescue fears.
• July 17, 1918: The royal family and associates executed by firing squad in a cellar.
• Initial reports suggested Nicholas was the only victim; later confirmed all were murdered.
• Rumors of Anastasia surviving sparked claims from several imposters.
• 1920: Young woman found in Berlin claiming to be Anastasia; later identified as Anna Anderson.
• Critics challenge her identity, linking her to a Polish-German factory worker with mental health issues.
• Anna continued her fight for recognition, losing multiple court cases until moving to the U.S. in 1968.
• In 1991, Romanov remains discovered; DNA analysis of remains conducted.
• mtDNA comparison with Prince Philip confirmed remains were those of the Romanov family.
• A missing daughter suggested Anastasia could have escaped; Anderson DNA analysis proved otherwise.

Paint Evidence

• Paint dries to a hard film of pigments and additives in a binder.
• Commonly examined are automotive paint finishes, with multiple coatings including:
  • Electrocoat primer
  • Primer surfacer
  • Basecoat
  • Clearcoat
• Forensic paint comparison uses stereomicroscopy for color, texture, and layer sequencing.
• Pyrolysis gas chromatography (GC) and infrared spectrophotometry aid in distinguishing paint formulations.
• PDQ (Paint Data Query) provides automotive paint information based on chemical and color data.

Glass Evidence

• Glass is a brittle, amorphous substance of silicon oxides and metal oxides.
• Tempered glass is stronger; laminated glass contains a plastic layer.
• Important properties for glass comparison:
  • Density
  • Refractive index
• Flotation method: glass density compared in a liquid until it is suspended.
• Immersion method: refractive index determined until it matches the glass particle's.
• Cracks from projectiles leave radial and concentric patterns to determine impact direction.
• Collect all glass pieces to ensure potential evidence is not lost.

Soil Evidence

• Soil's value lies in its prevalence and transferability at crime scenes.
• Comparisons are made by color and texture of soil specimens.
• Forensic geologists characterize soil based on mineral content and other debris.
• Collection involves gathering reference soils from surrounding areas for comparison.

Review Topics

• Recap on trace evidence: hair DNA, mtDNA, Russia's royal family, and types of evidence including paint, glass, and soil.