Tuesday, February 22, 2011

RESEARCH: Crime Scene Investigations

I’m thinking this week should have a theme so, in line with the brief book review from yesterday, I’m going to do all of my posts today based around crime scenes and the crime genre. Today is, of course, the research day, so let’s take a look at some of the research I’ve done for a roleplaying game I’ve run for the World of Darkness (any excuse for research is a good excuse). A note to authors: this information could be comprehensive enough for your first draft but due to regional differences, try to double check these sorts of facts with a local pathologist or crime scene investigator. They’re generally happy to help.

Crime Scene

When a Medical Examiner comes across a crime scene, they are hoping to establish the cause of death (the injury or disease that led to the death); mechanism of death (how they actually died – blood loss, cardiac arrest, etc.); and manner of death (whether the death is a homicide, suicide, accident, natural death, or unknown).

First, they examine the crime scene in a systematic manner to gather additional information or evidence before moving over to the corpse, if any. The corpse is photographed extensively and then the Medical Examiner declares the person deceased and looks for any obvious injuries. The body may be rolled over, examined for obvious injuries of the back, photographed again if any are found, and then plastic bags are placed on the hands and feet as a lot of trace evidence can be found on these body parts (especially under the nails. The corpse is wrapped in a white sheet brought to the location by the crime scene investigators. They don’t use sheets found at the home because that would contaminate the corpse with trace evidence from the person’s home, for instance loose hairs, fibers, etc. could fall on the corpse. Once wrapped in the white sheet, the corpse is then put into a body bag and a tag on the body keeps track of where the body goes and to whom it goes so that the Chain of Evidence can be established.

Autopsy Room
The corpses are stored in refrigerated units that might be found in drawers along a wall of an autopsy room (open the cupboard door, pull out the tray) or adjacent to the autopsy room in a room that looks like a collection of steel tray pigeon holes. These units are often kept at around 3.3 degrees Celsius which is cool enough to delay decomposition without being cold enough to freeze and damage the tissues.

The autopsy room itself is well-lit, generally windowless, and air conditioned. The autopsy table is generally two-tiered with a perforated and curved top tier to allow body fluids to drip down into the collection tray during the autopsy. A metal stand beside the table contains a range of implements from scalpels to serrated knives, clippers to scissors to magnifying glasses. The room is also often equipped with U.V. lighting, X-Ray machines, hanging scales to weigh organs, and vibrating bone saws. A microphone is suspended from the ceiling for the Medical Examiner to record their findings. Sinks and cupboards stand against the walls. Tissue samples are placed within collection bottles and envelopes. A Sharps contained can normally be found in this room.

The Autopsy
The body bag is examined before being discarded for any trace evidence that might have fallen out of the white sheet. Then the white sheet is unwrapped and discarded. Photographs are often again taken at this point with special care taken to photograph any newly revealed evidence. The clothes are then inspected for any tears, holes, or trace evidence before being carefully removed and stored for later examination. The bags around the hands and feet are then removed and inspection.

Finally, attention is paid to the body itself. Nails are examined and then scraped beneath the nail for any trace evidence. A detailed examination of the naked body is made, first with the naked eye, and then with a magnifying glass. All wounds, scrapes, bruises, etc. are noted, photographed, and measured.

X-Rays may be taken to look for any metal objects (bullets, fragments, knife tips) or abnormal structures or breakages in the bone. The Medical Examiner then views the body under Ultra Violet light which reveals body fluids (semen, blood, etc.) and even very faint bruising.

The internal investigation is begun with a Y-shaped incision whereupon all the internal organs are removed and examined from trauma and disease (these will later be replaced inside the body cavity). Samples of blood will be taken from the heart and peripheral veins, urine samples taken from the bladder, and sometimes even thin slices of organ tissue are taken. In cases of suspected rape, vaginal, oral, and rectal samples will be taken. Special attention is paid to the stomach contents as within 2 hours of eating, 95% of all food has moved out of the stomach and into the small intestine. The contents themselves can also confirm or deny witness statements such as if someone said the deceased had a home-cooked lasagne with them when evidence of a Big Mac and chips were found.

The neck may then be dissected to look for damage to the cartilage, larynx, or the small hyoid bone which would suggest strangulation. The brain is then dissected to see if injuries to the brain match injuries to the skull. As the brain floats relatively freely in brain fluid, it moves a little when the head is moving. To determine if an unmoving head was hit by a moving object, the Medical Examiner would check to see if the injury to the brain was directly behind the bruise (called a “coup” injury). If the victim’s head was moving at the time of the impact, the bump on the head should oppose brain injury (called a “contra-coup”).

Bone marrow samples may also be taken in some cases of drowning to search for minute single-celled organisms called diatoms that should have been breathed in unless the victim was already dead when they were pushed / dropped / fell into the water. A gas chromatograph can also be used to check the blood and tissue samples for toxins but the investigators need some idea of what to test for and it can’t be used to do a comprehensive check of every possible toxin.

Next week, Wounds, Decomposition and Much, Much More!

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