Mapping techniques Flashcards
What are the 4 stages of forensic recovery?
- Location – searching for the remains above or below ground.
- Mapping – grid the site to ensure detailed documentation of recovery.
- Excavation (where appropriate)
- Collection – proper packing of remains for further laboratory-based analysis.
What are key variables in forensic context?
- Depth of time
- Intent of placement
What are indicators of forensic circumstances to assess?
- Location of remains
- Position & orientation of body
- Preservation state
- Associated artefacts & evidence
What are the types of search areas?
- Open
- Obstructed
- Submerged
What are the different search methods?
- Aerial reconnaissance
- Walking grids
- Remote sensing
What do all search techniques be in accordance with?
“All techniques used must comply with relevant legislation and be demonstrably fit for defined purpose(s).”
What are questions to ask when locating remains?
- When did the event occur?
- Height and weight of individual?
- How deep was the body buried?
- Was the body wrapped in anything?
- Was the body clothed?
- What were the local conditions in the area?
- Was anything placed over the grave to conceal its location?
- Were there any unique landmarks?
- Has the landscape changed since the burial?
What search method is best for small teams or hillside areas?
Spiral
Spiral search method
- Works best for small teams or hillside locations
- Ensures no inadvertent trampling of evidence
- Reverse pattern used for searching for scattered remains
Strip/line search method
- Most common
- 100% coverage if properly executed
- Each line directed by team leader in middle of line
- Forensic specialist walk behind the line and inspect marked items of interest
Grid search method
- More time-consuming variation of strip/ line search
- Advantage: multi-directional and multi-angled search
- Helps account for light-mediated
revealing/obscuring of evidence.
Quadrant/zone search method
- For detailed searches of small areas
- Often implemented after remains have
been found
What are the different types of search method?
- Spiral
- Strip/line
- Grid
- Quadrant/zone
What are indicators of surface deposits?
- Skeletal remains and soft tissue
- Clothing, personal objects and weapons
- Decomposition odour and staining
- Insect activity
- Loose trash or brush heaps
- Animal activity and scavenging
- Materials used for wrapping body
What are indicators of buried remains?
- Mounding of dirt
- Primary burial depression filled with leaf litter
- Ground cover that varies from surrounding plant growth due to disturbance of topsoil
- A burrow possibly from a scavenging animal
- Mixed soil
What are indicators used to locate buried bodies?
- Skeletal remains and soft tissue brought to the surface
- Clothing or personal effects
- Insect activity
- Evidence of animal digging and scavenging
- Abandoned tools or weapons
- Soil or vegetation disturbance (Growth, lack of growth, colour change)
- Depressions, soil disturbances or unnatural mounding of soil
- Soil colouration changes from the mixing of soil layers
- Decomposition odour
- Decreased soil compaction
- Areas where bushes or tree limbs have been moved to conceal something
What are cadaver dogs?
- Specially-trained dogs to detect scene of human decomposition (whole bodies, body parts, body fluids).
- Dog tracks scent cone
How do scent cones work?
Primary, wind, water
- Primary scent pools form above and around decomposing remains
- Variable winds can cause uneven dispersal of scent molecules or multiple scent cones around the remains
- Water may move the scent away from the source in response to currents, gravity, surface or underground waterways, erosion or drainage patterns
Where do scent voids form?
Scent voids near the remains can form in areas where water flow interrupts the absorption of decomposition fluids into the soil or in cases where the body is elevated in relation to the ground surface.
Why do scent cones form?
Scent cones form as scent molecules are dispersed away from the source by airflow or thermal uplifting.
What may scent barriers form?
Scent barriers may form remote secondary scent pools and scent cones
What are the three types of probes?
- T-bar
- Penetrometer
- Soil-coring
What does a t-bar measure?
Qualitative changes in soil compactness
What does the penetrometer measure?
Quantitative changes in soil compactness
What does the soil corer check?
Check for mixing of soil horizons
What’s the problem with probes?
- Not useful over larger areas
- Can be destructive
What should you do when mapping a recovery site?
- Set up a datum on a permanent structure and note the GPS coordinates of the point
- Set up a grid over the area of the remains 3-4 meters square with four wooden posts connected with strings
- Tape measure from the height of string to document the location of each artefact of biological item.
- Detailed photography
What are the non-destructive parts of excavation & recovery?
- Examine & record the recovery area
- Establish spatial controls & record secondary surface deposits
What are the destructive parts of the excavation and recovery methods?
- Expose & record primary surface deposit
- Remove loose debris one grid at a time
- Remove/trim surface vegetation to expose remains for recording & mapping.
- Record and map all exposed evidence.
- Remove surface remains
- Examine soil layer beneath surface deposits
- Remove any buried remains/evidence.
What are the different methods of locating remains?
- Conductivity meter
- Resistivity meter
- Magnetometer/metal detector
- LiDAR
- NIR
- Ground-penetrating radar
- Side-scan sonar
What does LiDAR stand for?
Light Detection And Ranging
What are the two types of LiDAR?
- Topographic surveying (land)
- Bathymetric surveying (aquatic)
What are the factors which affect resultant elevation?
- Burial context (number of individuals, size of grave, completeness of backfilling)
- Time elapsed since burial (soil settling, decomposition, organic debris accumulation)
What are the two types of elevation changes?
- Change to the full extent of the grave/disturbance footprint
- Change directly atop interred bodies
What can a side-scan sonar be used to locate?
Submerged remains
What are the methods for mapping recovery sites?
- Total station
- Photogrammetry
How does a total station work?
Azimuth
❑ It uses a combination of stadia rods (known
height, marked with known measurements) and transit (precision telescope for recording measurements on the stadia).
❑ Record distance, azimuth (angle) & change in elevation for accurate mapping of items relative to fixed point.
How could you excavate and record a burial feature for buried remains?
Corner
- Working from the corner & across the grid, remove soil in 5 cm layers using a hand trowel & brushes.
- Screen all soil removed.
