Maggot Wash

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Forensic Taphonomy
and
Forensic Entomology
Jason Linville University of Alabama at Birmingham
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Taphonomy

• Definition
• The study of the conditions and processes by
  which organisms become fossilized.

• Forensically, the focus is usually on the
  days-years time frame rather than processes that
  occur over thousands of years.

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Taphonomy

• Reconstruct the circumstances of death

Estimate the time of death
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Taphonomy

• Forensic Anthropology

Usually deal with skeletonized (older) bodies.
Approximately 6 months for surface burial.
Can interpret

• General weathering of the bone
• Damage by carnivore scavengers
• Trace elements (vegetation, gunshot residue)

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Taphonomy

• Forensic Anthropology

Any time since death estimation is just an
estimation. It can be very difficult when
dealing with skeletonized remains.
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Forensic Entomology
Jason Linville University of Alabama at Birmingham
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Todays Seminar

• Forensic Entomology Background

Estimating the Postmortem Interval (PMI)
DNA Analysis of Maggot Crop Contents
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Forensic Entomology Background

• Definition
• Study of insects and their arthropod counterparts
  that interact with legal matters.

Urban Entomology
Stored Product Entomology
Medicolegal Entomology
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Forensic Entomology Background

• Definition
• Study of insects and their arthropod counterparts
  that interact with legal matters.

Urban Entomology Stored Product
Entomology Medicocriminal Entomology
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Forensic Entomology Background

• Definition
• Study of insects and their arthropod counterparts
  that interact with legal matters.

Urban Entomology Stored Product
Entomology Forensic Medical Entomology
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Forensic Entomology

• Insects and other arthropods can be used to
  answer

How or where a death occurred?
When did death occur?

• Postmortem interval (PMI) Time between death and
  discovery of a corpse

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Forensic Entomology

• History

• China - 13th century - sickle

• Bergeret - 1859 - dead baby

• Megnin - 1890 - fathered forensic entomology

• Hall - 1948 - blowflies

• Greenberg, Nuortova, Marchenko - 70s, 80s

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Flies and Beetles

• Definition
• Study of insects and their arthropod counterparts
  that interact with legal matters.

What is an arthropod? What is an insect?
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Flies and Beetles

• Arthropoda (phylum)

(class) Arachnida (spiders, scorpions) (class)
Chilopoda (centipedes) (class) Insecta (insects)
(order) Hymenoptera (ants, bees, wasps) (order)
Blattaria (cockroaches) (order) Diptera
(flies) (order) Coleoptera (beetles)
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Flies and Beetles

• Arthropoda (phylum)

(class) Arachnida (spiders, scorpions) (class)
Chilopoda (centipedes) (class) Insecta (insects)
(order) Hymenoptera (ants, bees, wasps) (order)
Blattaria (cockroaches) (order) Diptera
(flies) (order) Coleoptera (beetles)
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Flies
Some (not all) flies are attracted to dead bodies.

• Carrion Flies

Calliphoridae (blow flies) Sarcophagidae (flesh
flies) Muscidae (house flies) Phoridae
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Flies

• Phoridae

• Scuttle flies or coffin flies

• Take advantage of physical barriers larger flies
  cant get to body

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Flies

• Calliphoridae (blow flies)
• Shiny color (bluebottle, greenbottle)
• Among the first flies to arrive at a corpse

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Flies

• Sarcophagidae (flesh flies)
• Large, gray flies
• Also among the first flies to arrive at a corpse

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Beetles
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Beetles

• Coleoptera (beetles)
• Arrive early or late in decomposition process,
  depending on species

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Flies and Beetles

• 1. Eggs

2. Larvae
3. Pupae
4. Adult
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Estimating the Postmortem Interval
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Estimating the PMI

• Collection of Insect Samples
• At the Crime Scene
• At Autopsy

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Maggot Mass
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Cellar floor in an isolated Italian farm house
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Estimating the PMI

• Collect Insect Samples

Kill Stops growth (keep some alive for ID).
Preserve Keeps identifiable features intact
Ethanol or Kahles solution
Collect Climatological Data
Environment affects growth rate.
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Estimating the PMI

• Once evidence is received, specimens are
  identified to the level of species.

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Estimating the PMI

• Identification of the specimen

Question Why is this important?
Answer Different species grow at different
rates
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Estimating the PMI
Timeline
Egg
Larvae
Pupa
Adult
Sarcophagid bullata
50 hours
110 hours
Sarcophagid cooleyi
40 hours
90 hours
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Estimating the PMI
Timeline
Egg
Larvae
Pupa
Adult
Sarcophagid bullata
50 hours
110 hours
Sarcophagid cooleyi
40 hours
90 hours
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Estimating the PMI

• Identification of the specimen

Sarcophagid bullata
Sarcophagid cooleyi
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Estimating the PMI

• Identification of the specimen

• Morphological means
• color, hairs and bristles, wing structure
• male genitalia

• DNA identification
• mitochondrial sequence of COI

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Estimating the PMI

• After evidence is identified, there are two
  methods for estimating the PMI

• Succession of insect fauna

• Estimating age of immature insects

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Succession of Insect Fauna
The corpse provides an attractive environment for
insects to feed, mate and deposit eggs.

• The corpse passes through relatively predictable
  stages of decomposition.
• Different species of insects will be attracted to
  the corpse at different times.

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Flies
Flies arrive early in the decomposition process.

• Calliphoridae
• (blow flies)

Sarcophagidae (flesh flies)
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Beetles

• Coleoptera (beetles)
• Arrive early or late in decomposition process,
  depending on species

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Succession Data
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Succession of Insect Fauna
Conditions affecting succession

• Temperature (hotter faster)
• Geographic Region (variable insect fauna)
• Other factors wrapped, buried, indoors

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Age of Immature Insects

• Since eggs are rarely deposited on a corpse
  before death...

The age of immature insect specimens is the
absolute minimum amount of time a person has been
dead.
For example A three-day-old maggot on a corpse
would indicate the body has been dead for at
least three days.
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Complete Metamorphosis
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Complete Metamorphosis

• 1. Eggs

• 2. Larvae
• 3 stages (instars)
• Stop feeding during 3rd instar

3. Pupae
4. Adult
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Growth Data
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Larval Growth Data
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Age of Immature Insects
Conditions affecting growth rate

• Temperature (hotter faster)
• Other factors drug use, day length

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Sample Investigation
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Sample Investigation

• Details of the Case
• Dead body discovered at the crime scene (900am)
• Maggots are found on the body
• Some maggots are collected and preserved, some
  are collected alive
• No irregular circumstances
• Main suspect claims to have seen the victim alive
  two nights earlier

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Sample Investigation
16 maggots
Additional maggots for identification
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Sample Investigation
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Sample Investigation
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Sample Investigation
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Sample Investigation
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Sample Investigation
Identifying the sample
Sarcophagid bullata
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Sample Investigation
Measuring the size of maggots
1.4
1.5
1.4
1.8
1.8
1.6
1.6
1.7
1.7
1.7
1.8
1.6
1.8
1.6
1.6
1.5
(cm)
Largest size
1.8 cm
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Sample Investigation
Length
3rd instar
2nd instar
1st instar
Time
Development Rate for Sarcophagid bullata larvae
at 25 C
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Sample Investigation
Length
1.8 cm
34 hours
Time
Development Rate for Sarcophagid bullata larvae
at 26.7 C
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Sample Investigation

• Climatic Information
• Day body is discovered - average temperature
  20C
• 1 day earlier - average temperature 21C
• 2 days earlier - average temperature 20C
• No other irregular factors

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Sample Investigation
Sarcophagid bullata
Largest size
1.8 cm
At 26.7 C it would take 34 hours to reach a size
of 1.8 cm
Accumulated degree hours 26.7 x 34 907.8 ADH
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Sample Investigation
Accumulated degree hours 26.7 x 34 907.8 ADH

• Day 1 1200am - 900am
• 9 hours at 20 C
• 9h x 20 C 180 ADH

• Day 2 1200am - 1200am
• 24 hours at 21 C
• 24h x 21C 504 ADH

• Day 3 ?
• 907.8 - (504 180) 223.8 ADH
• ? h x 20 C 223.8

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Sample Investigation

• Day 3 ?
• 907.8 - (504 180) 223.8 ADH
• ? h x 20 C 223.8 ADH

223.8 ADH / 20C 11.2 hours
11.2 hours
9 hours
24 hours
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Sample Investigation
11.2 hours
9 hours
24 hours
44.2 hours at actual temperatures
34 hours at 26.7 C
Victim murdered before 100pm two days before
discovery
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Sample Investigation

• Suspect confesses to crime