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Trace Evidence > Soil > Flashcards

Soil Flashcards

1
Q

Private sector in soil examination:

A
  1. International Union of Geological Sciences Initiative on Forensic Geology.
  2. Working on Guide to Forensic Geology and Code of Conduct.
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2
Q

Potential benefits of soil materials as trace evidence:

A

Soil can be collected by non-specialists at a particular position or place where something occurs or is situated.

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3
Q

Forensic soil examination:

A

Often comparative rather than being focused on identifying on a particular soil.

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4
Q

Laboratory recovery is relatively simple:

A

This cannot be said of soil sampling at the scene of the crime.

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5
Q

Team approach to crime scenes:

A

Careful consideration needs to be given to the sequence of examination and sampling by specialists to maximize potential for each to ensure their work is not compromised and to minimize potential negatives for other specialists.

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6
Q

Principle responsiblities of crime scene examiner:

A

Recognize, record and recover.

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7
Q

Critical skill of Crime Scene Examiner or any specialist:

A

Recognize anomalies or inconsistencies which may indicate a potential evidence discovery.

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8
Q

Geologist:

A

Interpret location and anomalies which might indicate burial site.

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9
Q

Most significant challenge:

A

Sampling

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10
Q

Crime scenes:

A

Vary by their nature; differ greatly

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11
Q

Samples should be:

A

Sufficient (adequate) and representative of possible variation.

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12
Q

Specific considerations for packaging:

A
  1. Place in folded paper and sealable plastic container. 2 Moist samples need to be passively dried. 3. Plastic bottles found in aqueous environments (river/swamp).
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13
Q

Spatial scale:

A

Geographical extent of an area.

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14
Q

Spatial resolution:

A

Resolution or spacing for a sampling strategy.

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15
Q

No simple rules with respect to number or size of samples to meet criteria:

A
  1. Specialist should consider classic crime scene search patterns. 2. Samples should have accurate geolocation recorded.
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16
Q

Forensic geology contributes to:

A

Development of the potential location for an incident.

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17
Q

May need to:

A

Conduct aerial examination, analysis of geology of area and ecology.

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18
Q

Human remains involved:

A

= 3D Layer Perspective

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19
Q

Soil classification help to:

A

Organize knowledge about soils and soil surveys.

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20
Q

Two international soil classification system:

A
  1. World Reference Base (WRB). 2. Soil Taxonomy.
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21
Q

Soil maps produced at different scales to depict soils over:

A
  1. Large areas such as the world, countries and regions (1: 100,000 or larger scale). 2. Detailed areas such as farms (1:10.000 or larger scale).
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22
Q

Countries sometimes have internal databases:

A

Parent material, climate, organisms, and amount of time it takes for these properties to interact wil vary worldwide.

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23
Q

Diversity of Human Made Soils. Human made and urban soils general terms used to indicate soils under strong human influence in urban - suburban areas:

A

Characterized by strong spatial heterogeneity: Brick fragments, compost, toxic wastes, mixing of original (natural) soil material. Mine soils. Characterized by diversity, heterogeneityand complexity.

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24
Q

Soils Categories in Forensic Investigations:

A
  1. Questioned samples whose origin is unknown or disputed (suspect or victim). 2. Control samples whose origin is known, usually from specific sites directly related to investigation such as known or proposed crime scene. 3. Alibi samples whose origin is known and provide a measure of the uniqueness of the questioned / controlled samples.
25
Q

Why is soil a good sample in forensics?

A
  1. Soil has high probability of transfer and retention. 2. Soil is nearly invisible (fine soil materials). 3. Soil can be quickly collected, separated and collected. 4. Soil can easily be characterized. 5. Capacity for computerized soil database.
26
Q

Targeted sampling:

A

Localized areas where distinguishing features are evident in soil (i.e. shoe print).

27
Q

Random sampling:

A

Used in cases where there is an absence of obvious features at or around location of interest.

28
Q

Forensic investigation of soil usually involves the following:

A
  1. Soil collection and sampling of one or more samples. 2. Soil characterization and evaluation.
29
Q

Soil sampling divided into two classes:

A

Targeted sampling and Random sampling.

30
Q

Soil profile usually consists of a:

A

Number of different soil layers or horizons with different properties.

31
Q

A soil profile is a:

A

Vertical view of the layers of soil from the surface down to the unaltered parent material and used in classifying soils.

32
Q

XRD methods:

A

Most significant for identification, characterization, semiquantitative and quantitative analysis of minerals in soil.

33
Q

XRD methods:

A

Extremely small sample quantities as well as large quantities.

34
Q

XRD methods:

A

Advantage: unique character of diffraction patterns of crystalline and even poorly crystalline soil minerals.

35
Q

XRD methods:

A

Non-destructive examination.

36
Q

XRD methods:

A

Identification via database of XRD data.

37
Q

Drift Spectroscopy main advantages:

A
  1. Non-destructive.
  2. Rapidly applied.
  3. Mid-infrared portion of electromagnetic spectrum is sensitive to organic materials, clay minerals, quartz because absorption of IR light at the vibrational frequencies of molecular functional groups constituting these materials.
38
Q

Soil characterization and evaluation:

A

Stage 1. Initial characterization for screening of samples. Visually compare samples with microscope. Use soil morphological descriptors: color, consistency, structure, texture, segregations/ coarse fragments, abundance of roots/pores.

39
Q

Soil characterization and evaluation:

A

Stage 2. Semidetailed characterization. X-ray powder diffraction (XRD), diffuse reflectance Infrared Fourier Transform (Drift), Mass/volume magnetic susceptibility method.

40
Q

Soil characterization and evaluation:

A

Stage 3. Detailed characterization. In cases of extreme small samples, pressed powder for XRD analysis not suitable. SEM and TEM are frequently used to examine morphology and chemical composition. FTIR. Bacterial community DNA profiles.

41
Q

Soil characterization and evaluation:

A

Stage 4. Integration and Extrapolation of soil information. Landform and soil mapping.

42
Q

Forensic Geoscience. Large scale global analysis of seismology:

A

Allowed to detect large explosions. Locate aircraft crashes remotely.

43
Q

Forensic Geoscience. Searching for buried objects:

A

Geologist makes desktop study of bedrock geology, surface deposits, soils, topography, past and present land use.

44
Q

Forensic Geoscience. Range of data will:

A
  1. Limit search area prior to any field.
  2. Assessments of diggability, thickness of soil /sediment
  3. Access route
  4. Places that have been altered identified.
45
Q

Forensic Geoscience. Medium scale.

A

Comparing soil, sediment or rock from suspects and victims to that from possible scenes of crime. Questions answered:
Where has deceased been? Where has the illegal package or vehicle been? What is the substance on a victim, suspect or material??

46
Q

Forensic Botany. Typical samples encountered in forensic botany.

A
  1. Partially digested food such as stomach contents, vomit and feces.
  2. Wood and wood fragments.
  3. Diatoms and other algae.
  4. Licit and illicit drugs including poisonous plants.
  5. Plant fibers used in the manufacture of paper and textiles.
  6. Nonspecific plant parts, or whole plants, often present as trace physical evidence.
  7. Pollen and Pores.
47
Q

Partially digested food, feces stomach contents and vomit:

A
  1. May identify last meal of deceased person.
  2. May help establish time of death or timetable of recent events.
  3. May place death in a window of time corroborate other indicators of time since death.
  4. During violent crimes, victim may defecate and traces carried away by offender.
48
Q

Plant cells resistant to digestion:

A
  1. Identify types of foodstuff present.
  2. Low/high power microscopy.
  3. Histo-staining techniques.
49
Q

Wood and other Plant Fibers:

A
  1. Includes pieces of timber or timber products used as weapons.
  2. Wood comes from softwood and hardwood.
  3. Wood is laid down through annual growth cycle.
    • Annual rings can be read to give history and parent tree.
    • Theft and illegal logging.
  4. Wood cells or fibers found in paper.
    • Examination part of document examiner
50
Q

Palynology is:

A
  1. Sub discipline of botany in which pollen grains are examined and identified.
  2. Describe and identify wide range of microscopic entities.
  3. Pollen and spores may persist for very long periods of time because of them being chemically robust.
51
Q

Plant Toxicology:

A
  1. Plants used for medicinal purposes because of natural pharmaceutical constituents.
  2. Many plants contain toxins as products of normal metabolic processes.
  3. Poisoning:
    • Accidental ingestion
    • Misidentification
    • Misadventure
  4. Including in plants are fungi - these may be consumed for hallucinogenic drug properties
52
Q

Diatoms and other algae:

A
  • Most common micro algae encountered as trace evidence.
  • Occur in many habitants:
    Marine, Freshwater and Terrestrial environments
  • Various species that flourish in generally inhospitable environments.
  • Diatoms have extremely resilient siliceous cell walls termed “Frustules”
    contain two valves.
  • Frustules highly resistant
    Diatoms most commonly associated with drowning investigations.
53
Q

Cannabis and other Plants:

A
  1. Most common plant material examined in forensic lab
    “Cannabis”
  2. Combination of microscopic features is unique.
54
Q

Identification of Herbal material:

A
  • Botanically “Cannabis Sativa” can be identified on the basis of microscopic features of the plant.
  • Namely the trichomes: glandular, unicellular and cystolithic.
  • All 3 present confirm “Cannabis Sativa.”
  • Glandular trichomes are the structures in which the “cannabis resin”
    is produced: found on the underside of leaves and occasionally on stems.
55
Q

Zone search method:

A

Used for well defined zones such as houses and buildings.

56
Q

Grid search method:

A

Used for outdoor scenes (double line method).

57
Q

Line method:

A

Used for large outdoor areas; requires effective coordination.

58
Q

Wheel or Ray method:

A

Used for small circular crime scenes.

59
Q

Spiral method:

A

Inward or outward; used on poorly defined crime scenes such as open water.

Trace Evidence (17 decks)

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