First Report (Due Nov. 17th)
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Format is up to you, but should be logically organized.
Each group needs to provide a report for the known
Victim
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Victim #1 (LaFayette Rd).
l  Documentation of decompositional stages
l  Documentation of all relevant environmental data from crime
scene
l  PMI Estimation from emerged flies for your Group
l  PMI estimation from maggot measurements
l  Digital copies of photos and properly labeled samples
Meteorology, Variation in
Succession, and Factors
Altering PMI Estimates
Forensic Meteorology
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Microclimatic Factors Influencing Temperature
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Elevation
Shade
Water
Substrate
Aspect
Urbanization
Utilizing remote (Off-Site)
Temperatures in PMI Estimation
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Given that microclimate has large influences on
temperature, we must be careful in utilizing
temperatures from one location as surrogates
for unknown temperatures at another site
Ideally (access to crime scene during a relevant
time period), FE s can measure temps directly in
the microclimatic environment of the cadaver.
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Allows for correction of temperatures from
nearby recording stations.
Allows more accurate estimation of the on-scene
thermal environment where the insects developed
Correcting Remote Temperature
to On-Site Conditions
Date
Airport
Max
Airport
Min
Site
Max
Site
Min
Aug. 13
21
14
20
14
Aug. 14
23
14
21
13
Aug. 15
25
17
24
16
Aug. 16
26
15
25
12
Aug. 17
31
21
29
18
Aug. 18
31
19
28
18
Aug. 19
24
15
23
15
Aug. 20
21
16
21
13
Aug. 21
24
16
23
15
Aug. 22
24
15
24
12
Cadaver Discovery
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Obtain values from
nearby site(s)
simultaneously with
recordings of on-site
temps for postdiscovery time period
using data-loggers or
hand-held thermometers
Correlating Temperatures
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Develop a mathematical relationship between the
remote location temperatures and on-site values
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Site Max Temperatures
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Airport Max Temperatures
Plot airport against site
values
Equation describes the
linear relationship between
on-site, post-discovery,
temperatures and the
remote site values.
Next step, correct
temperature values prior to
cadaver discovery
Going back in Time…
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Date
Airport Max
Temperatures
Site Corrected
(y = 0.8125x+3.4875)
Aug. 12
25
23.8
Aug. 11
24
23.0
Aug. 10
27
25.4
Aug. 9
28
26.2
Aug 8
28
26.2
Apply correction equation to chosen remote site values
for dates prior to cadaver discovery
Assumes that the relationship for post-discovery is the
same as it was prior to discovery
Air Temp
Body Temp
Maggot mass complicates calculations!
l  Data from Pig 1 2015 at Lafayette Rd
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Variation in Successional Fauna
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Geographic Locality
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Seasons
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Competitors (including other blowflies)
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Habitat
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Shaded vs. open, forest vs. field or roadside, wet vs. dry
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Urban vs Rural
Enclosed Space
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Car trunk, house, wrapped in blankets or plastic
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Some species will not enter enclosed spaces like dwellings
Condition of body
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Size / weight frozen, buried, burned, submerged, disarticulated,
wounds, body moved after death.
Geographic locality
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Presence of the introduced Chrysomyia in southern
US.
Cochliomyia macellaria is a migrant in the northern
US, appearing by late summer
Protophormia uncommon or absent in southern US
We are starting to accumulate data indicating that
there are significant regional differences in
developmental parameters within a species (e.g.,
Lucilia sericata, P. regina)
Seasons
Species composition and diversity change with
seasons
l  Highest diversity in our region occurs late in
summer (5 or more blowfly species may be
present).
l  Obligate diapause for some species (especially
Lucilia) occurs in fall, complicating rearing.
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All or most of the population may arrest their
development as contracted maggots in the soil until
the following spring
Habitat
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Urban and rural
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L. coeruleiviridis vs. L. sericata
C. vomitoria vs. C. vicina
I did a small paired study this fall using pork bait
at Lafayette Rd and just down the hill along the
81 Overpass
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C. vomitoria and L. coeruleiviridis at Lafayette Rd
C. vicina and L. sericata underneath the overpass
Phormia and L. illustris at both sites
Outside versus
inside
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Indoors tends to be slower
and with fewer species
involved
Initial colonization is often
delayed.
The number of maggots may
be smaller due to smaller
numbers of ovipositing
females
Indoor environments are
highly unnatural for many
species (light regimes, lack of
pupational substrate, etc).
Day 17
Day 17
Secondary Oviposition
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Under some conditions, there may be discrete waves or
bouts of oviposition.
Leads to distinct developmental cohorts or even distinct
generations
Must be careful to get maggots or puparia from the first wave
Some sources of error and their
effects on PMI
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Based on relatively few of the thousands of maggots
we could have sampled.
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By chance, samples may not capture the largest individuals
of a species (error – PMI too recent)
By chance – the precocious maggot!! (error – PMI too early)
Inappropriate temperature data (error – either way)
Developmental rate not well known for a species (error –
either way).
Maggot mass temperature not accounted for (error – PMI too
early)
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Air temps tend to under-estimate degree-day accrual!
May not have been the first species to oviposit (PMI too
recent)
Case example from 2011
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Three species of adult flies from samples
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Phormia regina (first adult Sept. 29th)
Lucilia coeruleiviridis (first adult Oct. 2)
Lucilia illustris (first adult Oct. 7th)
Phormia ADD = 191.4 (Greenberg (1991)
L. coeruleiviridis ADD = 207 (Parry unpublished)
L. illustris ADD = 252 (Anderson 2002)
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Sept. 12, 2011
Sept. 19, 2011
Phormia eggs
Timing of Oviposition
Phormia is not always an early colonizer
l  Some research suggests that it does better,
its growth is facilitated, by the presence of
other blowfly species.
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Maggot mass
temp. above
ambient
Maggot length
Phormia colonize
Phormia emerge
Time
Lucilia colonize
Lucilia emerge
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?
Forensic entomologists tried to establish a timeline using the following
data collected from the girls decomposing body.
l  Found blowfly larvae (3rd instar):
l  Calliphora vicina
l  Lucilia sericata
l  Phormia regina
l  Adult Calliphora
All of these are typical early successional species
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Also found adults of:
l  Hister beetles (Histeridae)
l  Rove beetles (Staphylinidae)
l  Dermestid beetles (Dermestidae)
l  Cheese skippers (Piophilidae)
All of these are late successional species
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How do you reconcile (or can you??) these data??
Variable Temperature
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Nearly all of the estimates of ADH and ADD
required for forensically important flies are based
on constant temperatures.
Some blowfly species reared at variable
temperatures exhibit accelerated growth (e.g. daily
alternating temps of 10 and 20 versus a constant
15).
Age assessments of the
maggots
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Are the biggest maggots the oldest?
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E.g., A Lucilia or a Phormia oviposits one day before a
Calliphora but by day 4, the Calliphora are the largest.
Always ID maggots, then:
Consult graphs relating age versus length for
specific species
The sun effect
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Sunny vs. shady sites may have a greater effect than
air temperature alone.
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Controlled experiment with animal cadavers for 16
days.
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Air temperature differences alone contributed 11% difference in
available degree-days.
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Heat loading of the bodies added an additional 13 - 33% (24 44% of the total) difference in degree-days
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Changes with cadaver size (larger mass – more stored
heat)
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Presence / absence of clothing (dark objects absorb
more heat)
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Changes with substrate (sand vs. soil. vs concrete).
Maggot Mass and Ambient Temperatures
vs Time for Pig One
45
40
35
30
Maggot Mass
Temperature
25
20
Ambient
Temperature
15
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10
5
0
0
100
200
300
Maggot Mass and Ambient Temperatures
vs. Time for Pig Two
50
45
40
35
30
25
20
15
10
5
0
Maggot Mass
Temp
Ambient Temp
0
100
200
300
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Maggot mass
temperatures increase
well beyond ambient
But relative differences
are larger in the shade
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.) slow maggot development
Cocaine speeds up development, heroin 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