In a scientific investigation, physical evidence plays a key role in linking the suspect and the victim to every alternative or to the crime scene. Evidence is visible, collected at the scene and sent to a laboratory for scientific examination according to the investigator's needs.

As all crime scenes are naturally different then almost anything can be considered as physical evidence depending on the type of crime and the circumstances under which the crime took place. According to section 1571 of the Indian Cr. P. C., the crime scene is a very rich source of various kinds of evidence. It must be thoroughly searched.

What Is Physical Evidence?

Physical evidence refers to any material objects that may be present at the scene, at the victims, or found on the suspect. Tracing evidence refers to the physical evidence available in small but measurable amounts, such as hair follicles, strands, or skin cells. The evidence gathered at the scene is analysed and the results used in a criminal investigation to prove or disprove the facts of the case.

Physical evidence can be considered as:

• Corroborative evidence, often confirming or supporting criminal theory,
• Circumstantial evidence, which indirectly gives a certain conclusion about crime.

They are also called real evidence and are indirect types of evidence, which include tangible subjects such as hair, strands, hidden finger and foot traces and other biological and chemical elements.

Locard's Exchange Principle

'Every Contact leaves a Trace'
The importance of tracking forensic evidence was first recognized by Edmund Locard in 1910. He was the director of the first existing criminal laboratory, located in Lyon, France. Locard's Exchange Principle states that "with the affiliation between the 2, there'll be associate exchange". as an example, burglars can leave traces of their presence and can follow the trail They could leave hair on their bodies or strands on their garments back and should take carpet strips away.

Types Of Physical Evidence

1. Paint:

   physical and chemical analysis of paint evidence (chips or residues) may indicate its class, such as car paint, house paint, nail paint, etc.
   
   Proof of paint can also show individual characteristics if the investigator is able to find similarities between two samples, such as colour, number of layers, chemical composition, or actual similarity between the edges of two paint chips, one from a tool and one from crime scene.
   
   Most of the evidence for painting comes from crimes involving hit-and-run cases. With a controlled sample comparison sample, the paint can be compared to a car with almost 100% certainty3.
    

2. Glass Pieces:

   Windows or glass windows, particles, or fragments found or transferred to a person or object involved in crime may be strong evidence.
   
   Such evidence, whether broken by a bullet or otherwise, helps to determine its colour, features, brightness, density, chemical composition, and refractive index.
   
   The test results provide clues about the crime and help investigators to link evidence with the suspect or other object used in the crime, such as matching glass from the crime scene to the suspect's car light.
   
   In addition, a lower surface is usually found for fingerprints and / or blood to be present in broken glass 4.
    

3. Explosives And Petroleum Products:

   Explosive and petroleum products are equipment that contains explosive charge, as well as all substances released from an explosion or heat source that is likely to contain residual petroleum material. The presence of these elements becomes an important factor in determining where a fire or explosion originated and where it continued.
   
   Another feature of petroleum products is related to adultery.
   
   For which appropriate collection and analysis helps determine the chemical composition of such materials that can help identify the origin and users of the material. Traces of explosives found on clothing, skin, hair, or other items of the suspect may be likened to explosives from a crime scene.
    

4. Ballisitcs:

   Guns, as well as ammunition or incomplete ammunition, are often the most important evidence in any shooting investigation. In fact, it is almost impossible to obtain a conviction for shooting cases without the discovery of such evidence. If anyone is accompanied by a suspected weapon, a bullet wound, or a case of a broken cartridge can be compared to a weapon and a fingerprint can be compared to a finger. The characteristics of ammunition, firearms and ammunition are examined to determine the similarities between the suspects and the evidence available at the scene.
   
   Chemical tests may reveal gunshot wounds (GSR) on the hands, face, or clothing of the victim or suspect to show how close the person was to the shotgun.
   Shooting at a barrel of a gun causes separate canals, bends, and scratches on the bullets, which can be likened to a shotgun.
   
   Police can search the National Integrated Ballistics Identification System (NIBIS) website to compare symbols from bullets, cartridge cases, and gun shells with ball proof 5.
    

5. Fracture Matches:

   When an object is broken, torn, or cut, two distinct edges are formed, called cracks.
   These ends can be compared with the naked eye or microscope to see if they fit together, indicating that they may have been part of the same object at the same time.
   Investigators may compare a piece of tape pieces, pieces of glass, pieces of paint, pieces of car accident, paper bag, etc. to find the same potential
    

6. Soil And Natural Resources:

   Any material (clothing or footwear) that contains soil, wood, natural resources such as minerals or other organic matter can help to link a person or thing to a particular place (for example, sandals embedded in a shoe and the vault insertion found in a garment). Many such samples do not prove to be identical, but it is possible by the presence of a rare object. Such types of evidence are often regarded as rare, but they are useful in supporting other evidence in a case6.
    

7. Questioned Documents:

   Any document in question, whether handwritten or handwritten, is sent to the laboratory for authenticity and source. These types of analysis are widely used for ransom notes, suicide notes, death threats, and fraud. When typewriters were used, it was easy to compare the typewriters with the products they produce. With the advent of inkjets and laser printers, comparing printed texts is almost impossible.
   
   The exception may be if the document can be printed in an unusual font or with a rare ink type. Since reducing the use of typewriters, document analysis is now more focused on handwritten texts. Although each manuscript is the first one, no one duplicates the same text twice. The designers are smart and clever while trying to reproduce the signatures. For these reasons, handwriting analysis does not usually provide 100% similarity.
   
   Summarizing other types of work in document fragmentation include fraudulent acquisition and replacement; handwriting comparisons; reconstruction of damaged documents; identify and compare printers, typewriters or copies used to produce text. Inspectors will analyse a ransom note or other document to obtain clues to link it to the crime scene or to a specific suspect. they will analyse the type of paper used, the printing method or handwriting method, and the type of ink7.
    

8. Impression Evidence:

   3D impressions naturally include tool marks, tire marks, shoe or footprints, compression of lost or soft soil, and all other types of track ideas, and markings on the skin or on various types of food 8.
   
   Shoe stamps and tire tracks:
   
   1. The resulting evidence may be captured, taped, or cast to match the suspect's shoes or tires.
   2. Investigators will examine the evidence to identify the type of shoe or tire based on its tread pattern and other visible features to provide clues to the case.
   3. Shoes and tires will also show patterns of wear after being used for some time as well as other features (scratches, nicks, cuts) that can be used to match the evidence with certain items. for example, shoe stamps can be compared to a suspect based on the way the shoes are worn because of the person's style of walking 9.
   Bite Marks
   
   1. Each of the 32 teeth in humans is different due to age and aging.
   2. Impressions and images of the bite marks left on the victim, attacker, or other object at the scene can often be associated with dental records10.
   Tool marks
   
   1. Small nicks and chips form on the edges of the tool as it is used, which can be used to identify similarities between the evidence and the suspects.
   2. Tools may also pick up blood stains or other items that can be tested or have raised fingerprints that can be raised11.

9. Drugs:

   Drugs are substances that violate the laws governing the sale, production, distribution, and use of drugs or chemicals and that need to be caught. A large number of perpetrators of some forms of crime are involved with drugs. Drug production is big business. With the advancement of technological advances and the easy availability of chemicals, it has become much easier to manufacture illegal drugs and it has become increasingly difficult to catch suspects.
   
   When suspected drugs are found at the scene or in the body, samples are packed and sent to a forensic science laboratory for analysis. Preliminary or spot tests to find out who the drug is. Further verification tests will determine the strength of the drug and its components. The identification of drugs was completed with the use of various instruments. Although such equipment is expensive and requires frequent repairs, the results of such tests are significant12.
    

10. Blood, Organ, And Other Physiological Fluids:

    Blood and body fluids (semen and saliva) will be tested for biochemistry and other analyses to determine your identity and origin and then your identity. By checking the amount, colour, and distribution of such liquids, the investigator may be able to predict several times what happened at the scene. A smear may indicate an attempt to clean or drag the body.
    
    An accident occurs when blood flies at an angle and hits an object. The 'exclamation mark' feature indicates where the movement is.
    
    After careful collection, almost every type of organ or living organism will undergo blood transfusions and DNA analysis.
    
    Toxicology tests may also identify the possible presence of a drug, alcohol, or poison Blood type, used to exonerate innocent people and identify potential suspects or victims, is still a useful tool. However, recent advances in techniques, tools, and collection processes have increased DNA testing into more common species.
     

11. Fingerprints:

    It is generally known that when a person touches a subject with his or her hands (according to Locard's exchange system) that the printing fingers are left behind. Such prints are called latent prints as they are invisible to the naked eye. The challenge for the palaeontologist is to develop to identify, these hidden documents to find their owners.
    
    In the past, matching these prints required a narrow field for the suspects, but with the use of computers and a large database, identifying the suspect's documents has become common place13.
    Investigators also identified unique features of the ridge on fingerprints that could be used to identify a suspect or a victim.
    
    AFIS (Automatic Fingerprint Identification System) is a website used by investigators at local, regional, and national levels to search similar to the fingerprints found at the scene.
     

12. Hairs And Fibers:

    hair and strands may be transferred from the suspect or the suspect's clothes to the victims and vice versa. For example, a suspect might take strips of carpet from his shoes or leave his hair behind in a crime scene.
    Hair can be examined to determine its origin, such as a human or an animal. Root hairs may be complete without DNA testing.
    Fibres are used to make clothes, carpets, furniture, beds, and bedding. It may be natural fibres from plants or animals or man-made synthetic fibres14.
     

13. Wounds:

    Wounds can often be likened to weapons or Armor on a weapon. Investigators may also be able to determine the size, shape, and length of a weapon. Wound analysis may provide indications of the victim's injury, the characteristics of the suspect (left hand, right, height, etc.), and the position of the victim and the suspect at the time of the incident15.

Case Laws

Nitish Kumar Murder Case 16

In this case, it was very difficult to find the person guilty because only a small part of the tent with his finger was left unburned. But with the help of forensic science a DNA test was performed and assisted in identifying and identifying the body by associating DNA with parents. This also enabled the Delhi High Court to identify the suspects.

Sushil Mandal Vs The State 17

In this case, the father of the deceased boy is an applicant who has challenged genetic results. A dead boy fell on top of a teenage girl who fell in love with a girl from his school. Thus, the parents of both families were asked by the school principal to examine the children. A few days later, the boy was found missing, and a week later, the body was found in a decaying lake, which is unbelievable. The petitioner could not identify the body, and the clothes were not there to identify him as his son. He filed a habeas corpus application in the Supreme Court against the girl's father and asked the Supreme Court to direct an investigation into the CBI (Central Bureau of Investigation).

The geneticist's DNA and DNA of the deceased were then combined with the applicant and his wife. There was also a skull superimposition test. The autopsy also found contact between the deceased and the body found. But the petitioner could not accept the truth. The truth emerged only when scientific experiments were performed. The Supreme Court relied on scientific experiments and the case was closed.

Conclusion Physical evidence can be a very important part of a criminal investigation. However, for that to happen, evidence must be gathered and analysed. In the case of a serious crime, all possible physical evidence must be gathered. Since other evidence is evidence of tracking, this means a complete search, or "finger" search of the scene.

The way search is conducted depends largely on the context of the incident, but it will usually focus on a body-like area, then work outside or inside around. In some cases, investigators will work on a grid design to ensure that nothing is missing. The body itself is an important source of physical evidence and a search of the strings or fingerprints will always be done before you are taken to the morgue.

If physical evidence will be allowed in court, then a series of stocks should be proved. That is, each person in charge of the evidence from their collection to their appearance in court must have already signed it. Therefore, the court knows who was in charge at each stage of the trip. Safety measures will be taken to prevent any contamination.

If the person presents at the scene, then examined the suspect, he or she may pass on evidence such as a piece of cloth at the scene to the suspect. Ideally, the same officer would not switch between the scene and the suspect's residence. If they do, due to limitations on the number of staff investigating the crime, they should be removed from the area and be able to prove to the court that they have done so.

Once the physical evidence has reached the forensic laboratory, it should be kept under safe conditions. It should be noted that the items do not decay under their storage conditions in the event of a long period before any criminal proceedings are instituted. There are several different laboratory techniques that can assist in analysing and identifying the source of physical evidence. For example, visual micro spectrophotometry is useful in identifying the chemical nature of pieces of paint or fabrics.

Usually, these will be compared with the most reliable samples or those taken from the suspect. It may not be all evidence that proves useful in solving a crime, but it is better for investigators to gather more physical evidence than less. If they know how to keep it safe and the best way to explain it in the context of other evidence, tangible evidence can be a powerful guide to the circumstances and the perpetrator18.

Conclusion
With the advancement of forensic science in recent years, forensic science has been used to justify crime on a large scale, and there are cases in Indian courts where forensic science can be considered illegal. This is because most of the laws or regulations that we follow in our country were established at a time when forensic science was not as consistent as it is now. For the same reason, the courts are moving in the traditional way as modern methods can be considered.

The main advantage of using the forensic science is to produce evidence to obtain a fair trial. This is so that the real criminal may be punished and not innocent. Legal evidence has always been helpful in many cases to identify the real culprit and then the court will punish him.

Forensic evidence is far more important than the general evidence presented in court. Although there are sometimes errors in the evidence, which is very rare. More and more professionals should be noted for always providing relevant information and evidence about the case, and that is why the case can be resolved that way. There could be more progress in the country by making our forensic science grow. This can create stricter rules for punishing the defendant.

End-Notes:

1. Procedure for investigation preliminary inquiry
2. https://lawcorner.in/
3. https://projects.nfstc.org/property_crimes/module01/pro_m01.html
4. https://lawcorner.in/
5. http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000016FS/P001104/M014071/ET/1456987395FSC_P1_M23_e-text.pdf
6. https://indianlegalsolution.com/forensic-significance-in-physical-evidence/
7. https://www.hilarispublisher.com/scholarly/physical-evidence-journals-articles-ppts-list-2098.html
8. https://indianlegalsolution.com/forensic-significance-in-physical-evidence/
9. https://indianlegalsolution.com/forensic-significance-in-physical-evidence/
10. http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000016FS/P001104/M014071/ET/1456987395FSC_P1_M23_e-text.pdf
11. http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000016FS/P001104/M014071/ET/1456987395FSC_P1_M23_e-text.pdf
12. http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000016FS/P001104/M014072/ET/1456987436FSC_P1_M24_e-text.pdf
13. http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000016FS/P001104/M014072/ET/1456987436FSC_P1_M24_e-text.pdf
14. https://www.hilarispublisher.com/scholarly/physical-evidence-journals-articles-ppts-list-2098.html
15. Nitish Kumar v State of Bihar 2019
16. Sushil Mandal v The State Represented 2014
17. https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/physical-evidence