![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
scottobearHAPPY BIRTHDAY TO THE GRAY PUMPKIN!
Follow-ups to that Office Bricolage link.
PRISONERS' INVENTIONS
Improvised Weapons of the American Underground
Yahoo's Image Search may be better than Google's Image Search.
I can still amuse myself for hours by typing in random word/word combinations.
The friendy-meme. (revised a mite)
In the comments section of this post:
1. Tell me one thing you like about me.
2. Tell me two things you like about yourself.
Then...
3. Look through the comments. When you see someone you know, tell them three things you like about them.
4. Do this in your journal so I can tell you what I like about YOU. (or just ask, and I'll tell you here.)
Crime scene creepy-crawlies play a major role
They are first on the scene of a murder, and they get straight to work. There’s no messing around. The evidence they gather can be crucial to reconstructing a crime and solving a difficult case. You could call them the ultimate Flying Squad.
But this special unit has no need for sirens and high-speed vehicles. To the inner circle, they’re known, not as the Scorpions, but as “insects in the service of criminal justice”.
In their ranks are five species of blowfly, a cheese skipper and two kinds of beetle that arrive at the scene in orderly succession – eight waves of undercover agents.
Fortunately, their secret information can be clearly decoded. Expert human colleagues known as medico-legal forensic entomologists – in plain language, insect buffs – use their science to help solve crimes.
There are only two such experts in South Africa: Professor Theuns van der Linde of the University of the Free State and Dr Mervyn Mansell, who is based in Pretoria on a contract to the United States Department of Agriculture’s Animal and Plant Health Inspection Services.
Though he lends his expertise to the police on a part-time basis only, Mansell has worked on about 150 crimes in the last decade. Forensic entomology can make an important contribution towards solving violent crimes, he says.
It forms a vital part of the formidable armoury of highly specialised crime-solving techniques that includes DNA technology, forensic dentistry, facial reconstruction, fingerprint technology and forensic archaeology. Together, these help in piecing together shreds of information to create a picture of what might have happened.
“The two most important things on the scene of a crime are to identify the victim and to establish the time elapsed since death, known in technical terms as the post mortem interval or PMI,” says Mansell.
“Forensic entomology comes into play with the PMI.
Besides being able to establish the PMI, we can tell if the body has been moved since death – as well as a host of other information, such as whether there are traces of poison, drugs or alcohol in the victim’s body,” he says.
Most of this information is gleaned from the maggots that infest a corpse. The presence of a particular species indicates how long a body has been exposed – the different species lay eggs at different stages of the body’s decomposition and at different times in relation to each other. To the entomologist, the stage of the maggots’ development represents a certain number of days, because each species of blowfly has a unique life cycle.
Attracted by the presence of blood, iridescent green blowflies are the first to find the body of a murder victim. They immediately start laying their eggs in natural orifices such as the nose and mouth, but also in any wounds or areas of congealed blood.
The maggots that hatch set to work on eating the decomposing tissue. In the process, they imbibe substances (such as traces of poison or drugs) that provide a library of clues to the forensic entomologist who collects samples of maggots from the body.
Although even the thought of maggots eating away the flesh of a corpse would have the squeamish hyperventilating, Mansell sees it purely as a natural biodegradation process.
“Insects have an important role in facilitating decomposition. And they’re adapted to use innovative techniques to exploit a limited, ephemeral food resource,” he says.
It is the role of the forensic entomologist to identify those insects that are the “primary indicators” involved in the biodegradation process; to collect them from the body and surrounds; and to make deductions (for example about the PMI) based on the information they yield.
Once a crime scene has been demarcated by an investigating officer, and a video and photographs are taken, then DNA experts collect evidence before anything is disturbed.
While this is going on, the forensic entomologist takes notes about the ambient temperature, the time of day, whether the victim’s body is exposed, if it’s in sunlight or shade, in a room or outside. He gets the photographer to take close-up shots of the insects and where the maggot masses occur on the body.
He also takes careful note of what insects and maggots are on the body and around it and even if there are any squashed underneath the body or clothing. If there are some underneath, it might indicate that the victim’s body had been lying long enough for flies to lay eggs and for them to hatch before it was moved – squashing the maggots in the process.
Using a pair of tweezers, he collects samples of maggots from each site on the body, preserving them in small vials of alcohol (and labelling them accurately). Live samples are taken and reared in the laboratory so that he can confirm their specific identity.
This rigid procedure is necessary to build up an accurate analysis (from an entomological perspective) of the PMI. While preparing a report that can ultimately be tested in court, Mansell also takes into consideration the prevailing weather, as well as that leading up to the discovery of the body (which he sources from the weather office nearest the scene).
“It’s important to know if a body might have started drying out and then been exposed to rain, as this would affect which insects are present,” he says.
The weather also influences the flies’ life cycles – high temperatures stimulate quicker development.
The main indicator species of a fresh body are maggots of the green blowflies (Lucilia cuprina) and (Lucilia sericata), which arrive at a corpse almost immediately and lay their eggs. The larvae develop quickly – under favourable conditions they can go from egg to pupa within five to six days.
They might be in the pupa stage for three or four days before the flies emerge (see diagram of life cycle). The other main indicator species, commonly found in summer, is the banded blowfly (Chrysomya albiceps), which “takes out an insurance policy before inhabiting a corpse”, Mansell says.
It waits about two days, until the lucilias have laid their eggs and they have hatched, so that, if the food re-source is depleted, its maggots – known as “hairy maggots” – can feed on the other larvae. Should hairy maggots be the only ones present, it is clear that a fair amount of time has elapsed since the body was exposed.
Next comes the copper-tailed fly (Chrysomya chloropyga), followed by the grey fly (Sarcophaga cruentata), which keeps its eggs in the female fly’s body and hatches the maggots from there. “It throws its kids into school at Grade 8 level so they can beat the others,” says Mansell.
Chrysomya chloropyga is prevalent in winter, having almost free rein of corpses at that time of year.
Mansell says other flies that have been crucial to solving certain cases are those that prefer to lay their eggs in a secluded place (their presence thus indicates that the body has been concealed).
Such preferences are known as “niche partitioning” and are developed to eliminate competition.
He says blowflies – especially the first three species mentioned – are active on a body in the early stages of decomposition.
“The maggots chew through the body wall and feed on the soft tissue, converting it into their own body mass. They then fall off to pupate in the soil or in clothing.”
Maggots can reduce a body down to its skeleton within less than a month, depending on climatic conditions. Their only competition is large scavengers.
In an urban situation, scavengers are limited to rodents, feral dogs and perhaps, on the outskirts of a town, jackals.
“Once the maggots have opened up a body, its fluids flow out and it begins to desiccate; the fatty acids hydrolise and the corpse develops a cheesy smell,” says Mansell.
This happens at an advanced stage of decay, about a month after exposure. Now the “cheese skippers” move in – those flies that have been named for their attraction to very mature cheese! Then, once the body has dried out completely, beetles that have adapted to feed on dry skin and hide arrive, followed by a beetle that feeds on hair.
Mansell says it’s the job of the forensic entomologist to analyse the insect guilds present; to identify the indicator species, as well as parasites that are there to prey on the flies’ maggots. He also has to cut out any extraneous information – species he calls “tourists or passers-by”.
“I note the stage of development of the maggots and extrapolate how long they’ve been there, taking into account that they take 12 to 18 hours to hatch. From this information, I can give the PMI or time a body was dumped.
“I also look at where the major masses of maggots are on the body. Apart from the natural orifices, the flies lay eggs in wounds. So whereas I may not say the victim died from a gunshot wound, or if there is a mass of maggots in the uro-genital area that the victim might have been raped, I can draw the pathologist’s attention to those areas.”
Details such as whether a victim has clothing on or not, and if they’re exposed or wrapped in a duvet, blanket or plastic, affect what type of maggot might be found (some species thrive in a more protected environment).
According to Mansell under some of these conditions he would have to factor in a delay between the time of death and when flies were able to lay eggs on the body.
It is just as important if there are no insects on a murder victim, he adds. This could indicate that the body had been dumped shortly before having been discovered.
An example from real life emerged at a crime scene on the East Rand a few years ago. Although the body had been buried, there were maggots on the victim’s clothes.
The maggots had been squashed under a plastic bag in which the body was wrapped. The presence of maggots clearly indicated to Mansell that the murder had taken place elsewhere and that the body had been moved and then buried.
Judging from his maggot evidence, he estimated the body had been exposed for four days before being buried.
The prime suspect consistently denied involvement. But when the police confronted him with Mansell’s finding, demanding to know why it had taken four days to bury the victim, the suspect responded that he’d taken three days, not four.
Incidentally, apart from revealing information from a body, insects can give plenty of evidence about the movements of a vehicle – such as a robbery getaway car.
Those insects that offer up their lives in the service of justice, by getting squashed on a windscreen or radiator grille, can give away plenty of secrets.
For example, to an expert like Mansell, they indicate whether a vehicle travelled during the day or night and whether it came from another area.
After gathering evidence from a crime scene, Mansell takes his live maggot specimens back to the laboratory, where he rears them for accurate species identification.
To date, he has relied on his expert knowledge of the life cycles of the different species to help him explain his rationale for giving a specific PMI in his report to the police.
However, this may soon be backed up by sophisticated technology to look at the
DNA composition of insects. This would entail using the Polymerase Chain Reaction technique, which replicates and amplifies DNA to do an analysis of samples from maggots collected from a crime scene.
Not only would this clearly differentiate species, but even discrete populations within species, which often differ at molecular level.
“We’re looking at the characteristics of different populations of flies to tell us if a body has been moved. So, for example, if the maggots we find on a body come from a Cape gene pool, we know a body has been moved after death,” he says.
According to Mansell, the police DNA laboratory in Pretoria is one of the most advanced in the world.
“There are competent scientific people in the police force. In addition to the skill of the investigative officers, the power of the police lies in its forensic laboratories and fingerprint and facial reconstruction divisions,” he says.
Unfortunately, as yet, no forensic entomologists are employed by the South African police force. Mansell became involved in the early 1990s when he was called upon to help solve the Moses Sithole serial murders.
“Investigators noticed lots of flies on the scene where there were nine bodies in various states of decay. They contacted Onderstepoort Veterinary Institute, which referred them to me.”
Although police investigators on the ground see the value of forensic entomology, Mansell believes they have not been able to convince those at the top that it’s an essential area of expertise to have in the force.
Common in the United Kingdom, Europe and in the United States, it has even become a staple of TV in such detective programmes as CSI.
But this specialised field is nothing new. It can be traced back a thousand years, Mansell says, relating a tale of 11th-century Chinese forensics.
Faced with a murdered villager, and a suspicion as to the likely murder weapon – a sickle – the local version of the police invited farmers to a festival where they were to take part in a sickle competition.
How did they manage to force a confession out of the guilty party? Simple. When the contestants laid down their sickles, a swarm of flies descended on one blade – attracted to the traces of dried blood. It was, as they say in the classics, a cut and dried case.
One of the offshoots of forensic entomology is maggot debridement therapy – when maggots, instead of surgery, are used to clean away (in this case eat away) necrotic or diseased tissue.
As a result of Mansell rearing maggots in his laboratory for species identification, he was approached by Dr Frans Cronje of the Eugene Marais Hospital in Pretoria, who was interested in experimenting with the technique, also known as biosurgery.
The two, with Professor Clarke Scholtz of the University of Pretoria’s Department of Zoology and Entomology (who has provided a site to rear the maggots), have embarked on a collaborative project, which has so far had positive results.
Mansell says their first patient, early this year, had venostasis ulcers and faced drastic surgery on his leg. After applying their “maggot therapy”, the lesions seemed to have cleared up.
It’s possible the same therapy may be useful in other chronic wounds that result from diabetic ulcers or dog bites.
A medical practitioner or wound care specialist places the sterilised maggots on an injury and keeps them in place with a dressing. They are carefully monitored to ensure the maggots do not start eating away healthy tissue (though Mansell assures that certain maggots are adapted to eat only necrotic tissue).
An added bonus is that these clever little guys excrete an antibiotic that cleans the wound and they secrete a bacterium (Proteus mirabilis), which destroys other bacteria in the wound.
In nature, when they have cleaned up a wound, they simply drop off and pupate in the ground. It is thanks to the clean-up job that maggots do on animals’ wounds, says Mansell, that many survive serious wounds from fighting or other injuries.
Similarly, during the Napoleonic wars, soldiers left on the battlefield apparently often survived because maggots infested (and cleaned) their wounds.
However, maggot debridement fell into disuse with the advent of antibiotics.
But now the wheel of fortune has turned and the concept has become so commonplace in Britain that you can mail order maggots and apply them to a wound yourself.
Mansell’s maggots are also gaining popularity among sport fishermen – as bait, that is. “We can rear bigger, fatter maggots than the fishing shops,” he quips.
Archives -
1 year ago - RSP poll, Gamma World Memories, How to shave a cat's nose, FCC shenanigans
2 years ago - Sniper strikes again, weird news, Cool Rubik's Cube, Bookworm (it's on my palm, as I type), Nice thoughts, Painting minis, AW community gets uppity. it's now deleted. Rote 560 with my bike in front, bathy-Newt
3 years ago - Colloidal silver, geek test, memories of my first adrenaline rush, Los Dias de los Muertos, pieces of eight
4 years ago - met agent orange, lite brite, 2am french toast run, painted desert dreams
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
no subject
Date: 2004-10-22 12:20 pm (UTC)In the comments section of this post:
1. Tell me one thing you like about me.
I REALLY like and admire how you are calm and reasonable (is that two? they go together, though)
2. Tell me two things you like about yourself.
good mediator, kind to animals
Then...
3. Look through the comments. When you see someone you know, tell them three things you like about them.
4. Do this in your journal so I can tell you what I like about YOU. (or just ask, and I'll tell you here.)
please tell me here.
no subject
Date: 2004-10-22 12:37 pm (UTC)no subject
Date: 2004-10-22 04:10 pm (UTC)no subject
Date: 2004-10-22 01:25 pm (UTC)just one?! i can't do just one, sorry. i love how smart you are. how silly you are. how loving and caring you are to the people in your life. you rock my socks big bro :D
2. Tell me two things you like about yourself.
i have a great sense of humor. and i'm a damn good mother.
no subject
Date: 2004-10-22 02:09 pm (UTC)I agree with your #2 answer wholeheartedly as well!
no subject
Date: 2004-10-23 01:06 am (UTC)no subject
Date: 2004-10-22 04:40 pm (UTC)Scottobear, you come across as a fun guy with a great sense of humour.
2. Tell me two things you like about yourself.
Heh. I'm funny and good to be around. :)
no subject
Date: 2004-10-23 12:43 am (UTC)lol i wish that was one thing!
2. i am a lover and a WARRIOR!!!!!!!!!!!!!!!!!!!
no subject
Date: 2004-10-23 12:53 am (UTC)Fight on with your LOVE-POWER!!
no subject
Date: 2004-10-23 01:07 am (UTC)no subject
Date: 2004-10-23 01:22 am (UTC)HAIRY HAIRY MAGGOTS!
Bleah!