- Evidence is anything which tends to prove or disprove the matter under investigation.
- Physical evidence is anything which is tangible no matter whether microscopic or macroscopic, related to the crime present at the scene of crime. It includes all the objects, living or inanimate, or in any other state.
- The most valuable possession is physical evidence which helps in investigation and leads to a successful conclusion.
- The evidential nature of physical evidence should be kept in consideration by maintaining the chain of custody.
- Physical evidence should be overlooked in each and every dimension of crime scene.
What Information Does Physical Evidence Give?
- It proves the guilt or innocence of the person.
- Physical evidence can do all the following things:
- Physical evidence can establish ‘corpus delicti’( refers to the principle that a crime must be proved to have occurred before a person can be convicted of committing that crime.)
- It can link the suspect with the victim or the crime scene.
- It can identify the person’s identity that belongs to the crime scene.
- It can prove the conviction wrong and exonerate the innocent.
- It can corroborate the victim’s testimony.
- When a suspect is confronted with physical evidence, he may admit his guilt which will automatically leads to a successful investigation.
- They are factual and reliable too. They can never turn hostile. As for once we can believe the facts but not the eyewitness’s testimony that tends to be hostile.
Type of Physical Evidences
There is diverse variety of physical evidences that are encountered at the crime scene. They can be anything which is tangible (things that can be perceived by our senses).
There are various Physiological body fluids found at the crime scene. Each of them has their own importance, analytical techniques, method of collection and preservation.
The fluids are found in either dried or liquid state. It can belong to either human or any animal.
These are sent to the serological department for the further analysis and reports.
- BLOOD: Blood is found in major of the cases such as murder, road accidents etc. Blood can reveal lot of information which can lead to the perpetrator. It is also used for DNA analysis, to find parental relationships etc.
- SEMEN: Semen can be found in the cases that involves sexual harassment. It can be found on the clothing of victim or suspect or on bed sheet etc.
- URINE: Urine can be found in strangulation or poison cases etc. It can be used for the detection of drugs, poisons or alcohol.
- SALIVA: Saliva can be found on the found items present at the crime scene and along with the bite marks. It can be used for analysis of DNA too if required.
- There are other physiological fluids such as sweat, menstrual blood, vomitus, faecal matter etc.
The impressions formed due to frictional ridges present on the finger are called fingerprints. The prints left at the crime scene are called as chance prints. They are either partial or complete. They can be latent, patent or plastic prints. Fingerprints are collected by fingerprint experts only as they are fragile. An error in lifting or developing can lead to permanent loss of the fingerprints.
- Any object such as table, glass, pen etc.
- The non-identifiable locations such as door knob, on weapon or any tool etc.
The impressions formed by the either bare foot or shoe are called footprints. These prints can reveal the information like gait pattern of the person, height, weight, shoe size, provided shoe prints are present in entirety.
- This can be found majorly at the entrance or the exit of the crime scene.
- Also, sometimes on the pathway which is followed by the criminal.
There can be any handwritten or typewritten document encountered at the crime scene. The authenticity of document may be in question or suspected. It can be used for identification purposes too. These questioned documents can be of any type such as financial, legal, personal, administrative documents, charred, damaged, obliterated, indented or bearing secret writings etc.
- It can be present on the table, around the victim.
- It can be there in any drawer around etc.
Tyre impressions are found in the cases that involves vehicles i.e road accidents. It can reveal the vehicle, its model number, whether the suspected vehicle belongs to the crime scene or not.
- On the site of accident.
- Around the pathway from where vehicle may have left the crime scene.
The bite marks are the impressions left by the perpetrator which reveals the teeth pattern and sometimes contains saliva also. These can be found in the sexual harassment cases mostly. It can lead us to the perpetrator.
- It can be found on the food items such as eaten apple, chewing gum etc.
- On the other victim such as on hands, face, chest , thighs, etc.
This includes any of the drugs in the form of powder, pill, capsule etc. they are seized in the cases of poisoning, trafficking of drugs or violation of laws regulating sale, manufacture and distribution of drugs.
- On the table around the crime scene or the almirah of the suspect etc.
FIBERS AND FABRIC
They can be either natural or synthetic. The transfer of fiber can establish a link between the victim and suspect. The fabrics of victim or suspect are collected too if present.
- On the bed sheet, victim’s clothing.
- On car seats etc.
This includes anything which consists of explosive substance or consists of the residue of an explosive.
- At the explosion site.
This includes any glass fragment broken from a large piece which is its origin too. This can be found in the cases such as burglary, murder, road accidents etc.
- It may be found adhering to or embedded in tyres of the vehicle.
- From the clothing of suspect, soles of the shoes etc.
Any firearm or discharged ammunition such as bullets, shells, pads etc. sometimes, the weapon and ammunition is identified that whether it is used or not.
- At the scene of crime, vicinity, with the perpetrator or hidden/thrown somewhere by him.
Hair are also found at the scene of crime many a times. Since we keep shedding hair all through the day without our knowledge. There is a high probability of finding it/them at crime scene involving struggle or self defense. It helps in establishing a link between suspect and victim. It can also be used for the DNA analysis.
- On the floor of the crime scene.
- Can be found on clothes, combs, brushes, beds, carpets and furniture.
- In rape cases, pubic hairs can be found along with semen sample, or around the genitals of the victim.
The internal organs of the body, specifically those within the chest (as the heart or lungs) or abdomen (as the liver, pancreas or intestines). The singular of “viscera” is “viscus” meaning in Latin “an organ of the body.
These are collected for toxicology examination which tells the presence of drugs or the poison. The viscera are collected in different amounts depending on the poisoning.
Paint is a protective coating applied on the buildings, vehicles etc. This can be found in the cases of road accidents, burglary etc. The paints exchange between two vehicles or vehicle to person is analyzed. It can be in dried or liquid form.
- Found on or near person or object involved in hit and run accident.
- From the clothing or from the road also.
- Transferred paint samples are found at the point of collision between two vehicles.
This involves the arson or fire cases. Petroleum products such as petrol, diesel or kerosene are analyzed. The debris is collected to extract the presence or absence of petroleum products.
- Containers that might have been used in transporting the oil or petrol etc.
- The objects which may have soaked the petroleum product such as paper, floorings etc.
- Any burnt suspicious object.
SOIL AND MINERALS
It is present on the crime scene in one or the other form. It can be found along with the footprints or on any clothes, shoes or vehicle. It can reveal the travel history of the victim and also whether the suspect is linked to the crime scene or not.
- Found on a suspect’s shoes.
- Found on the carpet, door mat etc.
A tool mark is referred to impression left on a surface by the tool which is used in the crime such as if any object is used to open the lock, it will definitely alter the originality and will leave the traces too. The impressions are analyzed.
WIRES OR CABLES
Steel wire ropes material finds its applications in the building, construction sites, marine and elevator industries, involving various types of lifting equipment such as mobile and tower cranes. There can be Catastrophic failure of these wire ropes can occur without warning, causing damage and endangering lives.
The failure of the rope wire can be for different reasons and can easily be detectable by the forensic examination.
This includes all the botanical (plant parts) evidences such as leaves, twigs, flower, pollens and spores. These materials can link suspect and victim to the crime scene. Also, they can reveal the travel history of a person provided the plant is indigenous to that particular area.
- Plant materials like twigs, fallen leaves, roots, can be found on clothing, shoes of the suspect.
- Pollen grains can be found in nasal cavities, hair of a suspect or a corpse. It can be used to zero in/out a place.
- These materials can also be found on the tyres of the vehicles.
Forensic palynology is the utilization of pollen and spores in solving legal issues, either civil or criminal case.