Post-Mortem Artifacts (Cont’d)
Aquatic Decomposition and Insects
Testimony
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William C. Rodriguez, forensic anthropologist, estimated PMI
of between Jan. 17 and Jan. 31 (Danielle didn't disappear
until February 2nd), but pressed by prosecutors, expanded
time frame to include Feb. 1 to Feb. 6.
Robert D. Hall, forensic entomologist, colonized by blow flies
"no later than Feb. 23 and no earlier than Feb. 12th, 2002.”
M. Lee Goff, forensic entomologist, PMI Feb. 9 to Feb. 14.
David K. Faulkner, forensic entomologist, PMI Feb. 16-18.
Neal Haskell, forensic entomologist, PMI between Feb. 14-21
Brian Blackbourne, San Diego Medical Examiner, Feb. 1-18.
Problem: Westerfield was under 24 hour surveillance after
Feb. 5th – so how could he have dumped the body in a way
that coincided with some of these PMI’s?
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Forensic entomologists tried to establish a timeline using the
following data collected from the girls decomposing body.
All of these are typical early successional species
Found blowfly larvae (3rd instar):
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Calliphora vicina
Lucilia sericata
Phormia regina
Adult Calliphora
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All of these are late successional species
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Adults of:
l  Hister beetles (Histeridae)
l  Rove beetles (Staphylinidae)
l  Dermestid beetles (Dermestidae)
l  Cheese skippers (Piophilidae)
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How do you reconcile (or can you??) these data??
Bioaccumulation
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Drugs and poisons
Maggots accumulate these substances as they feed.
Can concentrate them at higher rates than found in the
cadaver
May change developmental rates
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Poisons (arsenic etc.) generally slow maggot development
Cocaine speeds up development, opiates slow it down
l  Significant PMI errors may be introduced
Methamphetamine speeds up development but greatly
increases maggot mortality
Detection of Two Narcotics
Case Study: Maggots on Coke
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20 yr old female, extensive
maggot colonization of upper
torso and face
FE identified two species, C.
cadaverina and L. sericata
Three size classes
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Most were 6-9 mm, indicating
development for about 7 days.
Smaller maggots (< 5 mm)
representing later oviposition.
Several maggots averaging
17.7 mm, corresponding to a
growth period of about 3 weeks
under prevailing conditions
Post-Mortem Artifacts
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Altered appearance
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Insects impart post-mortem changes to the cadaver
that could be interpreted as ante-mortem
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Larval movement
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Wounding
Sexual assault
Maggot movement through fluids produces trails that
can obscure evidence or be interpreted as antemortem movement by the victim
Adult activity
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Blood spatter versus fly specks
DNA acquisition / contamination
Fly Artifacts
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Adult flies have potential for altering post-mortem
crime scenes, especially blood evidence
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Track through blood pools or droplets
Feed directly on blood reducing droplet size or changing
shape
Regurgitate or defecate (so-called ‘fly specks’) after
feeding on blood or decompositional fluids
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Fly specks react positively to standard blood detection
chemicals used in forensic investigation AND will contain the
victims blood (or perpetrators in some instances)
Fly specks mimic blood droplet patterns associated with other
forensically important causes (cast-off, velocity spatter, etc).
Fly Artifacts
Regurgitate
Specks (Fecal
deposits)
Tracking
Characteristics of Fly Artifacts
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Assume artifacts are present if flies found at
scene (dead or alive)
Often concentrated at light sources
Characteristic tail/body ratio (>1)
Distinct tadpole or comma shape
Small (< 4mm) symmetrical with clear, white,
or yellow center
Wavy or irregular linear structure
If large concentrations found, directionality will
be random
High velocity spatter (gun shot)
Fly artifacts
Bedside Lamp
Ceiling Light
Preservation or Contamination
of Human DNA by Flies
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It is possible to recover full or nearly full DNA
profiles of humans from obligate blood-feeding
insects
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Human head, body, pubic lice
Fleas
Mosquitoes
Adult blowflies will consume blood or other
human secretions (e.g., vomit, saliva, semen) at
crime scenes
Considerable interest in whether recovery of
usable DNA is possible
Recovery of DNA from Blowflies
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Controlled laboratory study (Durdle et al. 2009)
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Lucilia cuprina adults fed on either human blood or semen
Fly ‘artifacts’ (regurgitate or fecal drops) collected and
assessed for usable DNA (> 0.1 ng)
Sufficient DNA recovered from 35-64% of blood fed fly
specks, 100% of semen fed fly specks.
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Blessing or curse?
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Could be used to implicate a
suspect in cases where crime scene
has been cleaned-up
Blowflies could introduce exogenous
DNA to a scene
DNA from Maggots
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Unknown victim found in Mexico (drug cartel war
related).
Partially burned and in advanced decomposition,
hands and feet cut off and missing.
No useable DNA from remaining tissue
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Although DNA profile was
incomplete, they were able to
recover enough to make a
conclusive match to the father
Aquatic Systems
•  Submerged cadavers - Fundamentally different process
than terrestrial decomposition.
•  No highly specialized carrion feeders
•  Most associated arthropods are opportunistic feeders or are
utilizing the cadaver as a substrate.
Environmental Factors and
Aquatic Decomposition
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Water temperature
Current
Salinity
Pollution
Siltation
Oxygenation
Submergence
Ice
Turbidity
Depth
2 weeks, warm
shallow water
7 months, deep
cold water
Colonization by Arthropods
•  Drift
•  Emergence
•  Organism Activity
•  Flooding/scouring
•  Point-source pollution
•  Currents
•  Siltation
Open wounds
Presence/absence of clothing
Insolation
Large scavengers
Competition, Predation, Grazing
• Drift
• Activity
• Presence of
algae/microbes
• Oviposition
• Diapause
Contrasting Terrestrial and
Aquatic
Sleeping bag
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Colonization of floating remains similar to
terrestrial environments.
Dead end for terrestrial species
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Blowflies colonize exposed tissue.
As they finished feeding and exited the
cadaver, consumed by small predators which
then attracted larger predators
The abundance of food created a novel but
short-lived food chain based on the transfer
of terrestrial resources to an aquatic
environment
Functional Feeding Groups
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Classification of aquatic organisms
based on how they feed.
Shifts in community organization
may be linked to succession
If predicable, could be used to
estimate a post-mortem
submergence interval (PMSI)
FFG
Representative Taxa
Scrapers
mayflies, caddisflies, beetles,
true flies
Shredders
stoneflies, true flies
Collector Gatherer
mayflies, stoneflies,
caddisflies, true flies, beetles
Collector - Filterer caddisflies, true flies, mayflies
Predators
beetles, true bugs, dragonflies
Black Fly Case
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Woman’s body found in a submerged
car in a deep hole beneath a bridge in
June 1989.
Cold water preserved woman’s body,
determination of time of death was not
possible
Ex-husband the prime suspect, but
claimed that after arguing in
September 1988, she drove away and
he hadn't seen her since. He swore
that friends of his had spoken with her
in the spring of 1989.
However, the black fly species using
the car for substrate has an extended
lifecycle and for them to be there, the
car would have had to be in the river
since October or November of 1988.
Suspect’s alibi subsequently fell apart