Forensic entomology and the relevance of MLT contributions

Borneo Scientific Meeting 2017Riverside Majestic Hotel;

Kuching, Sarawak,26th-27th July, 2017

Nor Aliza Abdul RahimDepartment of Paraclinical Sciences,

Faculty of Medicine and Health Sciences,Universiti Malaysia Sarawak

IntroductionForensic science is the application of sciences such as physics, chemistry, biology, computer science and engineering to matters of law.

Forensic science facilitate investigators to understandEg: blood spatter patterns (physics),

the composition drugs and trace materials (chemistry)determine the identity of an unknown suspect (biology).

Physical evidences are analyzed to provide scientific based informationfor solving criminal cases.

Branches of forensic science

Forensic entomology: the science and study of insects and other arthropods related to legal investigations.

: involved utilization of insects at crime scene to help solve crime cases particularly involving death.

Calliphoridae: blow flies

Sarcophagidae: flesh flies

Muscidae: house flies

Order: Lepidoptera: butterflies

Order: Coleoptera: beetles

Insects of forensic importance

Use of insects as evidence in solving crime

In order to analyze samples from crime scene, existing forensic insect database is crucial.

1. an established insect life cycle (duration for each species)

2. insect succession pattern at the localities

3. database of common decomposing insects at the localities

4. climate influence on the development of insects in the localities

General Fly

Life Cycle

Decomposition process and insect succession

Upon death the body will undergo decomposition processes.

Fresh Bloated Active decay

Advanced decay

Dry remains

Fresh stage –enzymatic breakdown of cells and tissuesBloated stage- metabolic activity of bacteria produces gases causing swell and pressure

pushes liquid out of orifices causing strong odorsActive decay stage -liquefaction and disintegration of tissue and odor persistAdvanced decay stage -decomposition rate decreases due to loss of mass Dry remains- only bones are left and no odor detected

Decomposition process and insect successionInsects will colonize the decomposing body in a successional pattern.Theory of 8 waves (Megnin,1894): Eight waves of arthropods come in succession in

chronological order on a corpse during decay.

carrion beetledust mite

butterfly

Insect wave

Corpse/carcass condition Insects group

First Few minutes after death blowflies, houseflies

Second Corpse/carcass start to smell several genus of blowflies

Third Fat fermentation beetles, butterflies

Fourth Protein fermentation group of flies and beetles

Fifth Ammonical fermentation houseflies, beetles

Sixth Slightly aqueous tissue dust mites

Seventh Dried tissues beetles, butterflies

Eight Bones or dry remains beetles

Order Family Species Kolej Kenanga, UNIMAS, Kota SamarahanStages

Fresh(Day1)

Bloated(Day 2-3)

Active decay(Day 4-6)

Advance decay

(Day 7)

Dry remains(Day8)

Diptera Calliphoridae Chrysomya megacephala - I, A I, A I, A -Chrysomya rufifacies - I, A I, A I, A -Chrysomya nigripes - - I, A - -Hemipyrellia liguriens - - A - -Chrysomya villeneuvi - - A - -Lucilia cuprina - - A - -Hypopygiopsis violacea - - I, A - -

Muscidae Musca inferior - - A - -Musca sorbens - - A - -Musca domestica - - A A AMusca sp. - - I - -Ophyra spinigera - - A A -

Sarcophagidae Sarcophaga sp. - A I, A - -

Hymenoptera Formicidae Crematogaster sp. A A A A AOdontomachus sp A A A A -Odontoponera sp A A A - -Pheidologeton sp A A A - -Oeophylla smaradgina A A A A A

Lepidoptera Lycaenidae Nacaduba berenice akaba - - A A -

Coleoptera Staphylinidae Unidentified - - A - -A – AdultI – Larva

Table 4.7: Insects species associated with each decomposition stage of rabbit carcasses at peat swamp forests.

• Climate or environmental changes can affect the life cycle of insects.• Climatological data (rain, temperature and relative humidity) and carcass

temperature are recorded as a reference to the duration of life cycle of insects.

Information useful for forensic entomology investigation:

Age and species of insect collected (to determine postmortem interval time, PMI)

Use of insects to determine PMI

Utilization of insects to determine PMI time is useful especially when under circumstanceswhere pathologist can only give broadapproximation.

Eg: bodies with extensive burnsbodies with advance decomposition

Use of insects to determine PMI

Roles of forensic entomologist

Before analysis can be conducted:

1. proper collection of specimen from dead bodies2. preservation of insects3. mounting of insects 4. identification of insects 5. proper storage of insects

All these need to be done with detailed and correct procedure.

Eggs, larvae and pupae • collected from various parts and around corpse.• killed with warm water and preserved in vials with 70% alcohol.• processed for mounting on slides for identification.• some are reared in laboratory on pieces of corpse tissues

for adult identification.

Collection and preservation of insects

maggotspupa

Collection and preservation of insects

Adults • collected using sweep nets • killed with chloroform or ethyl acetate using killing jar• transported in the killing jar to laboratory before pinning for

identification.

Sweep net

Killing jarPinned adult flies

Task conducted by a trained police officer or forensic scientist

• Insect specimens from crime scene must be kept in a properly locked compartment or safety cabinet.

• Proper storage is required because those insect specimens are of medico-legal importance andwill be presented as evidence in court.

Storage of insects specimen

Can a Medical Laboratory Technologist contribute in forensic entomology?

• Also known as medical laboratory scientist (MLS) or clinical laboratory scientist (CLS).

• MLTs are known to have roles and specific skills in laboratory and hospital where they work with samples and perform various diagnoses.

Who are the Medical Laboratory Technologist (MLTs)?

General roles of MLTs in hospitals

In hospital, MLTs assist physicians in diagnosis of diseases.

• Performs haematological, immunologic, histopathological,cytophatological, microscopic and bacteriological diagnostic analyses.

• Handle sample from body fluids: blood, urine, sputum, stool, cerebrospinal fluid, peritoneal fluid, pericardial fluid etc.

• Prepare tissue for microscopic examination by pathologists. • Help determine blood type. • Assist in medical research and analyses. • Operates and maintains

sophisticated instruments and equipment.

In universities, MLTs roles are more towards teaching learning activities. They assist lecturers in

• Set up for practical classes • Prepare specimen for teaching• Purchasing disposables and small equipment• Keep up with equipment maintenance

schedule• Assist in research laboratory for many disciplines:

microbiology, biochemistry, physiology, pathology, parasitology, entomology and etc.

• Assist in field works.

General roles of MLTs in universities.

Possible contributions of MLTs in Forensic (Entomology) Unit in hospitals • insect collection and rearing• sample processing and mounting• identification, photo taking and data entry• specimen safekeeping• reporting

Possible contributions of MLTs in universities:• field work and insect rearing• sample processing, mounting and storage• identification, photo taking and data entry

With proper training, MLTs can assist in forensic entomology investigations andcontribute to expedite preparation of insect evidence for expert witness use.

Possible contribution of MLTs in forensic entomology?