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article imageChemist uses blow fly eggs as forensics tool

By Tim Sandle     Jul 5, 2017 in Science
Something new for the world of forensic science: solving crime mysteries with the help of blow fly eggs. With this, experts can establish the body’s time-of-death to within a few hours.
Someone dies, perhaps murdered. Blow flies are often the first carrion insects to arrive and lay their eggs on a dead body. This natural fact allows forensic entomologists to study the arrival order and growth rate of different species of blow fly eggs. By looking at what is found on a corpse, new research clearly demonstrates, can help establish the body’s time-of-death to within a few hours. Such information can probe vital in helping to solve the circumstances behind a murder,
Blow flies a members of the family Calliphoridae. The flies shiny with metallic coloring, often with blue, green, or black thoraces and abdomens. There are some 1,100 known species. The maggot larvae, often used as fishing bait (and here as clues for crime scene investigators), are called gentles. The name "blow fly" derives from an older English term for meat that had eggs laid on it, which was said to be fly blown.
There's one downside with the process: blow fly eggs are microscopic and not easy to differentiate in terms of the stage of development. Moreover, it can take days for forensics experts to accurately classify them. To overcome this 'tiny' limitation, researchers from the University at Albany have a solution. The brainchild behind this is organic chemist Dr. Rabi Musah. For this the chemist got together with forensic entomologist Dr. Jennifer Rosati.
The outcome of this partnership was to develop a three-minute rapid chemical analysis. At the basis is mass spectrometry, an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio:
The application of this long-standing chemistry method allows a researcher to quickly classify blow fly eggs by fly species based on differences in amino acid profiles. Commenting on this process, Dr. Musah says: "Our analysis is the first demonstration of a rapid chemical fingerprint-based method for blow fly species identification from eggs."
The academic adds: “Differentiating insect eggs on corpses is of great forensic importance. Each species has its own development timeline, and therefore species identification of entomological evidence such as eggs can allow estimation of how long a body has been dead."
To test this out, the science groups deployed six pork liver traps which were placed around the Manhattan area to capture various blow fly species just before they laid eggs. Later, in the laboratory the scientists trapped blow flies and identified them by species using the mass spectrometry method. Next, the flies were given fresh liver on which to lay their eggs. The study of the eggs revealed differences in free amino acids between the species. Such analysis would reveal time of death, within a few hours, and rapidly, in relation to a crime scene.
The research is published in the journal Analytical Chemistry. The research paper comes under the title "Species Identification of Necrophagous Insect Eggs Based on Amino Acid Profile Differences Revealed by Direct Analysis in Real Time-High Resolution Mass Spectrometry."
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