Even the greatest crime investigator in history relied on the only true witnessevidenceto solve a crime. Although fictitious, Sherlock Holmes techniques of acute observation and logical application of detail underlay the basis of solving any crime. Those skills, added to todays growing technology allow police efforts to successfully conduct an investigation.
Since evidence is stable and will not change its story once in front of the jury, or forget what it saw, those who collect, analyze and interpret the crime scene play very important role. Forensic science is science applied to answering legal questions.
Under the rules of forensics, evidence is broken down into four categories:
TESTIMONYstatements from witnesses under oath
DIRECT EVIDENCEeyewitnesss accounts
CIRCUMSTANTIAL EVIDENCEinformation that may disprove or prove a point
REAL/PHYSICAL EVIDENCEany tangible article etc. (fingerprints, weapons, blood)
It is the accumulation of all the above evidence types that weigh down the case at hand. Physical evidence is attained through forensic analysis and is most useful in cases involving homicide or foul play.
When the call comes into the dispatcher at the police department, notifying the police that there may be a murder, an officer arrives on the scene to preserve the crime scene and control the situation until the Homicidal unit arrives. Once the expert detectives arrive, there is an assessment of tiny details to large details that were noted about the crime scene. Examples of the more obvious noted details are like whether or not the lights are on, or if the doors are open or closed, and location of furniture as well as body.
The rest of the process is handled by various individuals with a certain area of specialty. Once of the most crucial facts to determine is time of death. Along with witness accounts and such, postmortem (after-death) changes are the most accurate
Because of the known fact that when we breathe, oxygen comes into lungs and is circulated through our system by passage of blood cells. Since every system shuts down up on death, bacteria begin to manifest and let out enzymes that produce gas by breaking down the body from the inside.
Consequently, the shade of blood significantly darkens and due to the force gravity, it sinks to the lower sides of the body as muscles begin to tense up. Within a half-hour after death, lividity occurs.
Lividity is evident when the part of the body facing the ground turns purplish in color. In the early stages, if the skin is pressed, it will temporarily turn white under pressure. Whiteness is not possible more than five hours after death. By the four-hour mark, the body is usually completely stiff; a process called rigor mortis, which begins with smaller muscles. Two to three days later, the muscles return to a relaxed state since the fibers have begun to deteriorate.
Also taken into account for time of death is the behavior of insects if the murder took place outdoors or in an area with bugs.
The division of this particular science is called forensic entomology. The scent of death attracts insects as naturally as it repels humans. A basic rule of thumb for entomology follows these time allotments: (Forensic Science by Andrea Campbell.)
10 minutes after death if in open air, flies lay 1000s of eggs in mouth, eyes, etc.
12 hours Eggs hatch and maggots begin to eat tissues
24-36 hours after Dry skin is consumed by beetles
48 hours later Spiders etc. begin to eat the bugs that are eating the body
A criminologist named Edmond Locard developed a theory in 1910 and it is referred to as the Edmond Locard theory.
This theory states that every time something comes in contact with another, it takes or leaves a part of itself or another. (The Missed Evidence, by Dwayne S. Hilderbrand.) It is also referred to as theoretical exchange when pertaining to homicidal incidents.
There are many types of evidence that fall under that theory. Body fluids are the most important, such as blood, semen, urine, saliva and sweat.
With a certain DNA analysis, then blood and seminal fluids can be traced to an individual and be very accurate in doing so. If not, it can at least be determined from what certain population group it belongs to. The manner in .