CSI London: Bugs and Bodies

Blog Category: Criminology

When the body of Leah Questin was found in a suitcase on farmland in Kent in September 2009, Metropolitan Police officers investigating her murder took a tip from CSI’s Gil Grissom and his fascination for bugs.

The activity of Blowflies and their eggs at the site of the corpse was crucial in working out approximately when Leah died. In this case it was some 12 days earlier. As a result the officers could focus on a narrower timeframe when it came to collecting crucial evidence including CCTV footage and mobile phone use and prioritising lines of enquiry.

It soon became clear that someone had been using Leah’s phone and withdrawing large sums of money from her account. Detectives quickly focused on the man she had recently met through the dating section of the Gumtree website: Clinton Bailey.

Bailey had killed the 37 year-old nurse after inviting her to his home in Brockley, southeast London, on 12 September 2009. And although the decomposition of her body prevented pathologists from working out the case of death, there was enough evidence to prove it was murder rather than accidental death.

The following year Bailey was jailed for life with a minimum of 30 years before parole.

This study of insects in connection with crime – forensic entomology – gained greater recognition thanks to the lead character in the US TV series CSI: Crime Scene Investigation. Gil Grissom’s fascination with bugs may have been creepy, but it often cracked a case that had foiled the human members of his team.

Forensic entomology can not only estimate the time since death, it can also provide evidence as to whether a victim has been stabbed or shot, whether their body has been moved from another location and the type of that location and whether there was a longer period of neglect or abuse before death.

Samples taken from insects that have fed on a body can also indicate what substances were present if the remains have decomposed too much to be analysed.

The insects in question include flies, beetles, bees, wasps, ants, butterflies and moths. The most commonly used by forensic entomologists are blowflies, otherwise known as bluebottles and greenbottles. Blowflies are generally the first to arrive at a dead body and provide the most accurate means to estimate the minimum period since death.

After the eggs are laid by the female blowflies, they hatch into tiny larvae about a millimetre long which grow into maggots to feed on the body before moving away to turn into adult flies, leaving behind a brown case

The time intervals between each stage, and the size of the larvae allow the scientist to estimate the minimum time since death. However, when the body is placed in a zip-up bag – as in the case of Leah Questin – this timeframe is disrupted.

It was this issue which led MSc student Poulomi Bhadra to carry out a three-month experiment titled ‘Factors influencing accessibility of bodies to blowflies’ to determine how what delay can be caused by physical barriers like zip-up bags.

Chicken liver was placed in zipped containers of varying types and exposed to flies both in the laboratory and outdoors.

Commenting on her study, Poulomi Bhadra said: ‘The research itself has been so interesting; we have obtained some surprising results so far and there is much more to investigate.’

Her study is one of more than 100 research projects which have been carried out as part of the Metropolitan Police’s partnership with King’s College London since 2001.

No doubt her findings will be of use to the Met’s Evidence Recovery Unit and its staff of more than 100 forensic scientists and 400 crime scene examiners, who together investigate more than 11,000 crime scenes every month – that’s well over 132,000 a year.

The Unit is also responsible for blood pattern analysis, shoeprints, fingerpint enhancement, fibre analysis, crime reconstructions and DNA sampling.

Read the full case summary of the murder of Leah Questin

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