The term ‘physical evidence’ involves any physical entity that can furnish some degree of proof or disproof. In a crime scene, forensic experts look for physical evidence. The evidences, such as objects found at the scene of crime, are known as physical evidence.

All the crime scenes are unique in nature. Hence, almost anything can be treated as physical evidence depending upon the type of crime and the circumstances under which the crime was committed. It may not be possible to mention the type of objects to be recovered as physical evidences in a particular case. Several different types of physical evidences like pieces of glass, paint, soil, semen, saliva, hair, nail clippings; finger and footprints are very commonly found at a crime scenes related to different types of cases.

1. Impression marks are another important kind of physical evidence. When an item like a shoe or a tyre encounters a soft surface, it leaves behind a pattern showing some or all of its surface characteristics, known as an impression. The collection and analysis of impression evidence found at the scene of a crime can often be very important to an investigation.
2. Fingerprints are perhaps the most significant type of physical evidence in most crimes. The technology of collecting and analyzing fingerprints has been well known for over a century and has been refined over the years. A fingerprint is important as individualizing evidence. It can fix a specific person to a crime, because no two individuals have ever been found to have the same fingerprints. If a fingerprint from the scene of a crime can be linked to a suspect, then an identification can be made. The courts readily accept fingerprint evidence, if it is properly collected and analyzed.
3. Some items of physical evidence, such as weapons, can be easy to locate and collect. However, the investigator must take care not to contaminate these items by, for instance, leaving their own fingerprints. Investigators generally cover themselves with protective clothing in order to avoid contaminating evidence at the scene.

Once physical evidence has arrived at the forensic laboratory, it must be stored under secure conditions. Care must be taken that items do not deteriorate under their storage conditions in case there is a long interval before any criminal trial begins. There are a number of different techniques in the laboratory, helping to analyze and identify the source of physical evidence.

The following types of physical evidence may be found in diverse types of crimes:

All suspected blood, semen, and other physiological fluids, whether liquid or dried, animal or human may be present to suggest a relation to the offence or person involved in a crime.

They help to identify the criminal and the victims of the crime.

Footprints may establish presence of suspect at the scene of the crime. It may give information on the number of suspects and their identification.

Teeth marks on fruits or other food or bite marks on the victims may lead to identification of criminal.

Tyre marks or track marks may make it possible to identify the vehicle suspects in an offence.

Any handwritten or typewritten document submitted to determine authenticity or source. It will include paper, ink, indented writings, obliterations and burned or charred documents.

Drugs include any substance in the form of powder, pill, capsule, vial, etc., seized in cases of poisoning or trafficking or violation of laws regulating the sale, manufacture, distribution or their use.

Any device containing an explosive substance, as well as all objects removed from the scene of an explosion that is suspected to contain the residues of an explosive.

Any natural or synthetic fibre whose transfer may be useful in establishing a relationship between objects and/or persons. If an adequate piece of a fabric is found, it may be shown to have been torn from a particular garment.

Any firearm, discharged ammunition such as bullets, shells, wads and pellets or even intact ammunition suspected of being involved in a criminal offence may enable the expert to identify the weapon and the ammunition with the offence.

Any glass particle or fragment that may have been transferred on a person or object involved in a crime and window panes of buildings or vehicles containing holes made by a bullet or other projectile are included in this category.

It may be any animal or human hair found at the scene of crime which may link a person with a crime.

Body organs and fluids submitted for toxicology examination to detect possible presence of drugs and poisons. This category will include blood for the presence of alcohol and other drugs.

Any paint, liquid or dried, that may have been transferred from the surface of one object to another during the commission of a crime. Petroleum products—Any petroleum product such as petrol, kerosene, diesel, grease, thinners on clothing of victim, suspect or from a crime scene which can be identified and compared.

Chemical stains or cosmetic stains on the person or clothing of the suspect can be identified. Firearm discharge residues can be examined for determining range of firing.

All items containing soil or minerals may be examined to link a person or object to a particular location.

Any object suspected of containing the impression of another object that was used as a tool in a crime.

Copper wires, traction wires, electric cables found in possession of suspect can be linked to the source.

Includes all stolen property vehicles, firearms, etc., submitted to the laboratory for the restoration of erased identification numbers or marks.

Any fragments of wood, saw dust, shavings, or vegetable matter like pollens, seeds, leaf fragments, etc. discovered on clothing, shoes, tools or vehicles that could link a person or object to a crime scene.

International Research Journal of Social Sciences: Vol. 2(4), 16-23, April (2013)