Murder, Maggots & Mysteries of Forensic Science
forensic entomology
-use of insects in legal investigations
-civil and criminal investigations
-primarily homicide investigations
-determine elapsed time since death or postmortem interval(PMI)
-accurate,sometimes only method available after 72h
History of forensic entomology
th
china-13 century
europe-1850`s
britain-1930`s
north america-1970`s
canada-1992
<35 forensic entomologists world wide
-10-15 in USA
-2 in canada
first witness to the crime
-arrive within minutes (not that quick in rain,cold,night)
-within 24h
-lay many eggssssss
-face and then down the body
elapsed time since death
-focus police investigations into correct time frame
-identification of victim
-missing persons records
-make or break alibis
-define list of suspects
-exonerate innocent
-2methods
-maggot age and development
-up to 2 months after death
-accurate to hours,days,weeks
-successional waves of insects
-2months to serveral years after death
-accurate to weeks,months,years (season)
immature stage of
-blow flies(calliphoridae)
-flesh flies
-house flies
arrive immediately after death
-lay eggs at wounds or/and natural orifices
Life cycle
eggs - larva-pupa-adult wounds/mucus – can feed
-just eat before becoming adult- accumlate food
-wet body (mostly water)
-envir:dry,dark- no one eat them
-higher temp(optimum) -high rate of development and shorter duration of development
-temp and species are important
maggot age&development
-analysis of insects stage of development
+temp records
+species
=date eggs laid and minimum PMI (MINIMUM!!NOT MAX!) (old may be blown away)
collect from the body, not the suroungings
Regina v. Truscott
-1959,14 years old Steven Truscott
-convicted and sentenced to'hang by the neck until he was dead' for the murder of 12 year old Lynne Harper,
primarily on a time line based on stomach contents
-sentence later changed
-2001- filed for review of his conviction
-2006-07 – new evidence heard by Ontario Court ofAppeal
-included testimony of serveral pathologists and 3 entomologists
-area of controversy
Summary
-high probable that if Lynne's body had been there by 19:30, she would have been colonized by blow flies prior
to sunset
-blue bottle flies definitely capable of flying and colonizing body at night in 30oC
judge's words
successional waves of insects
-body goes through rapid physical,chemical,biological changes
-different stages of decomposition attracyive to different insects
-predictable sequence of insect colonization
insects species present at discovery
+evidence of species previously present
+evidence of species that have not yet arrived
=PMI
hierar
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