Lecture 22 Trace Evidence

1. Lecture 22 Trace Evidence Soil and Paint

2. Soil

3. Structure of Soil • Soil Forms in Layers or horizons • The term soil is also used loosely to refer to virtually any unlithified material at Earth's surface regardless of whether it has undergone the soil forming process known as pedogensis • O horizon: decaying organic matter. • A horizon:Under O horizon - or topsoil : consists of a mixture of mineral and organic material. • B horizon:Consists of slightly altered mineral material, • C horizon: Consists of unaltered but loose parent material from which the soil developed (for example, sand). • R horizon: If intact rock is present, it can comprise an R horizon. • K horizons: Desert soils rich in calcium carbonate (K used to avoid confusion with the C horizon) that range from light accumulations of calcium carbonate to so-called petrocalcic horizons (limestone formed in place) • Materials that do not fall under the strict definition of soil include sand in dunes or along beaches and mud deposited by a recent flood. • Soils form (pedogensis) by a complicated process influenced by factors: • Temperature, • Precipitation, • Mineralogical and chemical composition of the parent material, • Soil from different locations can have different physical and chemical characteristics • useful to forensic scientists.

4. Forensic Examples • The fictional British detective Sherlock Holmes is generally credited with the first use of soils as forensic evidence in the late nineteenth century. • Holmes could distinguish different soil types • Used that information tomake inferences about the travels of suspects. • Georg Popp: German Scientist • Credited as first forensic scientist to utilize geological evidence to solve a crime. • Used goose droppings, sandstone fragments, and three different kinds of dust on a suspect's shoes • Linked materials found at a murder victim's home, • Where the body was found, and the place where the murder weapon was found.

5. New Jersey Case • Soil found with body inside a plastic garbage bag • Identified as material dredged from Newark Bay • Used as fill to create new land along the shore. • Analysis of soil with body led investigators to the victim's wife and daughter, • Who killed him and temporarily buried the body beneath their home, which was built on the fill.

6. California Case • Soil found in a murder suspect's car partially, • Not completely matched the soil around an oil well where the victim's body had been dumped. • Research showed that gravel from a different location had been spread around the well. • Explains why soil from the car was not an exact match with the natural soil in the area.

7. Soil CollectionOpen Areas

8. Systematic Soil Collection 10’ 2’ 5’

9. C9 C17 C10 C8 C1 C2 Point of Origin C16 C7 C3 C11 C6 C5 C4 C14 C12 C13 Soil CollectionGeometric collection pattern 1 Approximately 3T should be collected from each area.

10. Soil Collection Geometric Collection pattern 2 C7 C12 C1 C8 C6 C2 Pointof origin C5 C3 C4 C13 C11 C9 C10

11. Collecting Soil • Collect exemplar soil samples from surrounding area of cast • Collect elimination samples from areas farther from impression evidence • Allows for assessment as to uniqueness of soil in that area • 1-3 Tablespoons should be sufficient • Collect samples from “alibi” sites • Shoe impressions: Collect top ¼” of soil • Excavation site: • collect @ different depths – mark depth • Open areas: • Use systematic method – make accurate measurements • Top surface • Most comparisons • Packaging Cast Impressions • Leave soil attached to cast • Package whole cast w/soil • Wrap in strong paper • Seal in strong paper bag or cardboard box Top Surface ¼” 1-3 Tablespoons Underlying Soil

12. Soil Collecting & Packaging • Collect soon after event • Changes to site may occur • Record exact location where collected • Ditch/roadside, etc • Next to house • Note landscaping • Note unusual conditions in vicinity – will affect soil content • Close to petroleum tank • Chemical plant – name plant • Seal • Air dry prior to final packaging – will affect comparisons • Prevents mold growth • Temporary packing @ scene if going directly to lab for drying • Pill box/vial • Label appropriately

13. Peeling Paint Paint Transfer Forensic Paint AnalysisCrime Scene Perspective Paint Layers Collecting Paint

14. Paint tells a story • Associates an individual or vehicle with a crime scene • Hit and Run cases—dried paint/paint smears transfers to clothing or vehicle upon impact • Identifies color, year, make, model of a car by paint recovered at an accident • Burglaries—paint can be transferred onto tools used to break into things Scene Vehicle Person Transfer The vehicle involved in a hit-and-run of a bicyclist who later died left white paint chips at the scene. Weapon Tools

15. Vehicle-to-Person • Victim to vehicle • Blood • Fabric impression • Vehicle to clothing of victim • Macroscene Elements • Imbedded into surface of fabric • Color of car • Part of car in contact with victim • Manufacture of car & year • Broken plastic @ scene can help ID car • Whole chips of paint • May contain several layers • May allow for physical match, e.g. fender of car • Microscene Elements • Smears • Small flakes Paint EvidenceHit-And-Run Cases • Vehicle-to-Vehicle • Vehicle-to-vehicle Transfer • One-to-other paint transfer • Cross transfer • Paint from each vehicle is transferred • Vehicle-to-Object/Person transfer • Transfer from vehicle to inanimate object • Telephone poles • Road barriers • Transfer to the scene • Road Surface Scene Vehicle Vehicle Transfer Object/ Person

16. Paint Composition • Paint is composed of a binder, pigments, and different additives • Most paint is applied in layers Layers

17. Paint Layers on Vehicles • Electrocoat primer—applied to steel body of car, provides corrosion resistance, pigmented gray-black • Primer Surfacer—smooths out and hides seams or imperfections (different pigments) • Basecoat—color coat; different additives add different effects (pearl luster, metallic look) • Clear coat—unpigmented layer, improves gloss, durability, and appearance

18. Why Collect Flakes of Paint? Source Attribution Layers Modern Automotive Paint Thin Layers of Each Paint Physical Matches Primer Multiple Layers of House Paint Clear Coat Paint Chips Physically Fitting Together Invisible Bottom Color Visible Vehicle Color Top Color

19. Collection From Vehicles • Must collect transfer paint & standard paint (exemplar) paint sample • Collect generous samples Damaged Area Exemplar Sample Headlight Damaged area Car Fender

21. Packaging Paint EvidenceGeneral Considerations • Larger Samples • Use small containers for larger specimens • Glass vials • Cardboard pill boxes • Small plastic bags or vials are okay • Smaller Samples • Use wrapped bindles • Seal in plastic bag or glass vial • Do not use paper envelopes • Unless sample is large • If used, seal ALL corners with transparent or fingerprint tape • Never lick an envelope

22. Collecting Paint EvidenceSpecific Considerations • From Garments • Collect entire garment • LAB removes paint imbedded into fabric • DRY Damp or bloody garments • Package in paper bags – not plastic • Wrap separately by rolling in paper • Avoid flakes from escaping • Avoid flakes transferring to other part of evidence • Seal bags with tape • Ensure that flakes cannot escape through the seams • Label appropriately From Vehicles • Document collection areas photographically • Collect transferred paint • Collect exemplar paint • Collect generous samples • 1/4x1/4” • Remove paint in flakes if possible • Sometimes can bend the metal a bit to get this done • Scrape if flaking doesn’t work • Clean scrapping tool first • Use disposable scalpel blades • Scrape into druggist fold • Never combine samples • Put individually collected paint samples into separate containers • Paint on one area may differ from damaged area • Color might appear the same • Repaired vehicles that are repainted

23. Burglary Paint exemplars • Near all areas where tool may have contacted surfaces • Include all layers present • Collect all areas touched by tool • Scrape into pill box, vial or paper fold • Small items • Take entire item, if possible • Guarantees all paint for analyst w/o loss • Burglary cases - Tools • Paint on Point of Use • Entrance to house • Jewelry box • Difficult evidence to locate • Paint on Tool • Transferred to entrance point • Secondary transfer Scene Transfer • NEVER ATTEMPT TO FIT TOOLS INTO IMPRESSIONS Weapon Tools

24. Toolmarks • Paint on Toolmarks • Collect specimens from all areas touched by tool • Scrape paint from relevant areas into pill box, vial or paper fold • Ensure that ALL paint layers present • Small items • Take entire item, if possible • This Guarantees all paint for analyst w/o loss Collecting Toolmarks as Evidence • Mark on packaging or on a tag attached to toolmark @ opposite end from where actual toolmarks appear • Mark cut ends appropriately • Package all evidence separately. • Cover toolmarks with bag and wrap with paper. • Never use tape on cut ends • After toolmarks protected, place in strong box and pack to prevent shifting. • Keep questioned specimens separate from known standards.

25. Malcolm Fairley “The Fox” • 1970s British Serial rapist • Detectives found yellow paint specks on a tree at one of the crime scenes • Paint analyzed—comes from a Austin Allegro car • Narrowed suspects—detective drove up at Malcolm’s house, found him cleaning a yellow Allegro • Examined car—found scratches on paint that matched paint flakes to the crime scene • Using this and other pieces of evidence, Malcolm was tried, convicted and sentence to 6 life sentences for rape, assault, and burglary

26. Gary Ridgeway“Green River Killer” • 1970s and 80s—truck painter who killed in Seattle area • Killed between 50-90 women and dumped bodies in the Green River • Ridgeway suspected but not arrested • Killing stopped and case went cold • 2001—case reanalyzed; • Paint on victims clothing matched to highly specialized paint used at Kenworth truck plant where Ridgeway worked • 2002— Paint analysis and DNA analysis • Ridgeway convicted of 48 counts of murder and • Sentenced to 48 life sentences

27. Forensic Paint Databases • Paint Data Query: PDQ • Maintained by the Royal Canadian Mounted Police (RCMP), PDQ contains chemical compositions of paint from most domestic and foreign car manufacturers and the majority of vehicles marketed in North America after 1973. • The software free to agencies that supply a minimum of 60 paint samples per year. The database information comes from the street (>60 percent from body shops and junkyards) and from manufacturers. • In 1998, RCMP entered into agreements with the German Forensic Institute and the Japanese National Police Agency, which resulted in 1,500 samples being added to the database each year. • Not all manufacturers, however, are willing to divulge chemical composition of paint used on vehicles. If a particular sample has not been entered into the database from the street, it would not be possible to obtain a match. • How does PDQ work? • Each paint layer (automotive paint usually consists of four) examined to determine the chemical composition – • Coded into the database. • Known samples are compared against a paint sample from a crime scene or a suspect’s vehicle to search the make, model, and year of manufacture of a vehicle involved in a hit-and-run or other criminal activity. Info: www.rcmp-grc.gc.caExit Notice. • National Automotive Paint File • FBI database: > 40,000 samples of automotive paint from manufacturers. • How does database work? • Paint chips from cars compared to samples in the database. • Undercoats help to narrow down possible manufacturers. Info @: 202-324-3000.

28. Other Categories of Trace Evidence

29. Building Materials • Seal in container and mark container-not projectile. Place CSI or investigator’s initials, date, case name and number on container. • Collect all available evidence • Use container such as a pillbox or paper bag. Seal to prevent any loss

30. Plant Material Cannabis, mushrooms, peyote, etc • Dry to prevent mold formation and collect amount over maximum penalty amount. • Loosely fill paper bag and seal if drying is impossible. • Use any suitable sealed container if dry. • Notify laboratory of condition upon submission.