Forensic investigators gather physical evidence and make detailed observations at a crime scene. Photographs are taken, witnesses are interviewed and a detailed theory of what happened is the result. In their book, Postmortem, Dr Steven A Koehler and Dr Cyril H Wecht describe the process of investigating a crime scene.
The First Responders to a Crime Scene
The first people to arrive at a crime scene are usually the police, fire department and paramedics. The medical personnel are responsible for checking for life in a body and declaring it dead-on-arrival if necessary. Once this has been done, the police will note the position of the body, and any apparent injuries.
The police are responsible for securing a crime scene and will encircle the death scene with police tape. An inner perimeter is set aside for active investigating personnel such as the coroner or medical examiner and the crime scene photographer. The following should be noted in the police report:
· Physical conditions such as a block of ice on the floor that may melt rapidly · Times of notification and arrival at the scene · Time of pronouncement of death · Identity of those present at the scene
Outdoor crime scenes are more difficult to preserve due to animal activity and weather conditions. Rain, snow and wind can destroy evidence such as footprints and blood spatters.
Calling in the Forensics Team
Once the crime scene is secure, the police officer will call the coroner’s office. The coroner is interested in any case where the death seems to be sudden, unexpected, unexplained, traumatic or medically unattended.
If the death warrants investigation, the forensics team will typically comprise two death investigators, a forensic photographer and possibly other experts who deal in ballistics, fingerprints, trace evidence and blood spatter.
Homicide detectives usually work in pairs and approach a crime scene with five basic questions:
· Did the death take place at the crime scene or elsewhere · Was there any attempt to alter the crime scene · Does the scene point to any particular activity such as drug abuse or burglary · Is the cause of death obvious · Are there sufficient clues pointing to how the death occurred
What Evidence is Collected at a Crime Scene
There are a number of specialists who deal with physical evidence from a crime scene. The things they look for include the following:
· Blood and other body fluids · Bones and skeletal remains · Fingerprints · Blood spatters and stains · Weapons and bullets · Hairs, fibers, traces of paint, soil and glass · Impressions such as shoe prints, tire tracks and tool marks · Documents such as wills and suicide notes
A thorough crime scene investigation is necessary for a cause of death to be determined and a murderer to be identified. Police and medical personnel work together at the crime scene and forensic investigators are called in to process the scene. By collecting all the evidence available, it is normally possible to identify the time of death, the cause of death and the killer.
Koehler, Dr Steven A and Dr Cyril H Wecht, Postmortem, Elwin St Limited, 2006.