Crime scenes are known to have many other types of evidence some are physical(DNA,fingerprints,Handwriting,photographs and clothing).Trace Evidence can be microscopic most Trace Evidence is small it can’t be seen with the human eye.Trace evidence is evidence left by an individual at the crime scene it can be either intentional or unintentional.
Trace evidence is left by touch and example would be if you had a really fuzzy sweater and a person brushes up against you,the fibers from your sweater would transfer to that person’s clothing . There are several different types of Trace Evidence such as fibers,hair,soil,wood,gunshot residue,pollen,chemicals and many other types.
Trace Evidence can be circumstantial an example would be if someone was murdered at a house and that person’s moms fingerprint was at that the crime scene,and the mom had visited a week ago the fingerprint has a reason to be there. However she still could have murdered her child so she will still have to be cleared as a suspect.Edmond Locard, founder of the Institute of Criminalistics at the University of Lyon, France, developed what has become known as Locard’s Exchange Principle.
This states that every contact leaves a trace (Trace Evidence). Investigators can potentially link a suspect and a victim to a location through trace evidence. Glass from doors or windows can stick on the soles of shoes.It can be found on clothes,tools,skin and weapons.Different types of glass break and shatter differently.Glass can also hold fingerprints.Dust and dirt can also determine where a person has been,where they have worked,where they live and if they have pets.
Pollen is also included in this this because it is a type of dirt and dust and can tell investigators if a suspect has been outside and where they have been.Forensic investigators must handle evidence from a crime scene with care so that they do not contaminate any evidence. Investigators have certain way of collecting ballistic evidence in order to prevent contamination and assure that it can be a valuable source of data.
The truth about how investigators deal with evidence is very far from the Hollywood image that has been created from shows. The accumulation of ballistic evidence can be broken down into collection of firearms, ammunition, and gunpowder deposits. In all cases, an investigator’s first priority is safety.
Before a firearm is sent to a laboratory, it must be checked to see there is no chance of an accidentals shot of a weapon. To be safe, in most cases a weapon will be unloaded. Some important things that investigators note in this process are the weapon’s safety position and the location of fired and unfired ammunition; this way, no evidence is lost.
Since trace evidence covers a wide variety of stuff, there is similar variety in the testing that is performed. Specialized testing may be done outside of the local laboratory at regional or national facilities. The type of test performed and the range of information provided vary by the type of evidence tested.
For example, analysis of a strand of hair may yield information on the race and general health of the donor, while analysis of a paint sample would probably find the manufacturer of the paint .Hair samples are tested primarily by microscopic comparison. Microscopic comparison identifies the shape, color, texture and other visual aspects of the sample.In some cases hair is subjected to DNA analysis. Trace evidence analysts usually have strands to work with.
From these strands, fiber testing is done using high-powered comparison microscopes to compare texture and wear in a side-by-side test. Chemical analysis can determine the chemical composition of the fibers. In the case of synthetic fabric or carpet, this information can be used to trace the product to the manufacturer using standards databases, further enhancing the probative value of the evidence.Glass can have valuable information through fracture marks, lines and patterns.
Testing for unique characteristics such as color, optical properties and density can determine the type of glass, for example a window pane, vase or glass bottle. Powerful comparison microscopes are used to compare colors, thickness and layer patterns, and luster or to match fragments and tears.
Blood Spatter is another thing that helps get rid of lunatics and murderers. One of the most important fields of forensic science is blood spatter analysis. Under the Crime Scene Investigation, analysts gather the information that could eventually lead to a victim’s killer. Basic and complicated information can be found when analyzing blood.
We can learn what kind of weapon was used, the time of death of a victim and other important facts that can help a case. The pattern that the blood gives off give forensic scientists the tools that they need to help solve cases. Investigators can find clues from a murder through a number of different ways. Typically they find out how many times an object hits a part of the body.
Stains that are on walls and/or ceilings can tell you that a lot of force was used.. A basic bloodstain pattern is known as transfer or contact. These are made when someone walks through a blood leaving footsteps or trails. Gunshot spatters are very common in crime scenes, and give off a sort of mist effect.
Sources of blood can reveal the origins of whatever it is investigators are looking for. If someone was interested in pursuing a career in forensics they would need a strong stomach or hardy exterior. The scenes can be gruesome and this job isn’t for everybody. Also work environment involves visiting morgues with hundreds of dead bodies.
A quality that is needed in this field is composure. Things do tend to happen so forensics and other technicians have to refrain themselves and get the job done. Critical thinking and problems solving skills are very important when solving cases that deal with quick decision making and the need of good judgment.
Every analyst needs to pay attention to detail because they need to notice the small things in order to collect good data.The first record of blood spatter was in 1895. Dr. Eduard Piotrowski of the University of Kraków published a paper titled “On the formation, form, direction, and spreading of blood stains after blunt trauma to the head.”