Exploring Physical Evidence in Criminal Investigations
When a crime is committed, investigators must collect evidence to help identify and prosecute the offender. Physical evidence is a vital aspect of any investigation, and when gathered and analyzed correctly, it can provide accurate and conclusive results. However, physical evidence is not always foolproof, and having a deep understanding of its nature is essential. This article will explore what physical evidence is, its importance in crime investigation, its collection, analysis, and use, the types available, limitations, and insights into its history in crime investigations.
What is Physical Evidence?
Physical evidence is tangible evidence that can be seen, felt, or touched. It can come in the form of anything that is found at the scene of a crime, or it can be discovered on a suspect’s person or belongings. Examples of physical evidence include blood, fibers, hair, fingerprints, footprints, and weapons. Physical evidence is significant in criminal investigations because it can provide investigative leads, link suspects to crime scenes or victims, and can be used to prove or disprove hypotheses.
Collection, Analysis, and Use of Physical Evidence in Criminal Cases
The proper handling of physical evidence is essential to prevent contamination or destruction of evidence. The process of collecting evidence must start as soon as possible after the criminal act has occurred, and it can often involve several people with varying areas of expertise. During the collection of evidence, it is vital to avoid anything that could change the evidence’s nature or condition. Once collected, the evidence is then sent to a forensic lab for analysis, where the scientific methodology is used to determine its significance. If properly utilized, physical evidence can significantly impact the outcome of a trial in a criminal case.
Types of Physical Evidence That Investigators Can Gather from a Crime Scene
There are six major categories of physical evidence – biological evidence, trace evidence, impression evidence, firearms evidence, arson, and explosive evidence, and chemical evidence.
Biological Evidence
Biological evidence includes bodily fluids, DNA, hair, and other body tissues. DNA evidence is one of the most common types of biological evidence and has provided relevant evidence in many criminal cases.
Trace Evidence
Trace evidence encompasses anything that is small enough to be overlooked, including fingerprints, hair, clothing fibers, and gunshot residue. Trace evidence requires a thorough scientific methodology to detect and identify the tiniest particles.
Impression Evidence
Impression evidence encompasses footprints, tire tracks, and tool marks like indentations, pry marks, and scratches, and can provide investigators with very specific information about the crime. With the use of specialized equipment, they can often be matched to the weapon that caused an injury.
Firearms Evidence
Firearms evidence includes bullets, shells, tools, and guns and is often used in forensic ballistics to see if a particular bullet and shell match a firearm of the same make and model or connect two crimes to the same offender.
Arson and Explosive Evidence
Arson and explosive evidence can include materials that have been set on fire, like gasoline or wood, or substances used to create an explosive device, like gunpowder or dynamite. These items can provide investigators with useful lead information.
Chemical Evidence
Chemical evidence can include substances like drugs, poisons, and other chemicals, and their identification can lead to more evidence and clue identification
Scientific Methods Used to Analyze Physical Evidence
Forensic scientists perform a range of scientific methodologies to analyze and examine physical evidence. These methods include:
DNA Analysis
DNA analysis is used to identify and compare genetic material from biological samples such as blood, saliva, semen, cheek cells hair, skin tissues, and organs. This method has significantly impacted criminal investigations alongside modern-day technology.
Fingerprint Analysis
Fingerprints are unique to every individual and are used for identification purposes. Forensic scientists use Fingerprint analysis to examine patterns, shapes, and other markings on fingers and hands. It is used to associate print patterns recovered from crime scenes with those recovered from suspects.
Ballistics Analysis
Ballistics analysis is a scientific methodology used to identify weapons responsible for gunshot wounds, bullets, and shells, as well as, reloading equipment and ammunition. Forensic ballistics experts use various techniques to study patterns and marks to compare evidence collected at the scene with firearms used by the suspects.
Forensic Odontology
Forensic odontology uses dental records to identify victims of crimes or accidents. With the technology used in forensic odontology, bite patterns can also be used to link an offender to a crime scene.
Forensic Toxicology
Forensic toxicology identifies the presence of toxins or poisons in the body of victims or suspects. Forensic Toxicologists can determine whether an individual was under the influence of drugs or alcohol at the time of the crime.
Other Scientific Methods
Several other scientific methods used in analyzing physical evidence, such as X-ray analysis, handwriting analysis, and tool mark analysis, can all provide valuable information that can help investigators solve crimes.
Limitations of Physical Evidence
Physical evidence is not always foolproof. Limitations of physical evidence at a crime scene can include;
Misleading or misinterpreted physical evidence
In some cases, crime scenes can misinterpret the physical evidence or make inaccurate assumptions based on physical evidence. It is essential always to have the investigation reviewed by different persons to prevent such outcomes.
Contamination of physical evidence
Contamination of physical evidence can lead to a wrongful conviction. Proper handling of the physical evidence is crucial, and it must start at the time of collection to prevent contamination.
Incomplete or inadequate physical evidence
In some cases, physical evidence might not be available or be inadequate to prove or disprove a hypothesis. This situation can be a result of improper handling or destruction of physical evidence.
Insights into the History of Physical Evidence in Criminal Investigations
Physical evidence has played a significant role in solving criminal cases. The early history of physical evidence dates back to the early civilizations when ancient Egyptians used fingerprints to identify gatekeepers. Today, with modern technology and scientific advancements in forensic science, physical evidence has become more reliable, and scientists now have a more comprehensive understanding of the role it plays in crime investigation. In the future, new techniques will be developed that will continue to improve on the already existing methods and equipment to make forensics analysis more accurate
Conclusion
Physical evidence is an essential aspect of any criminal investigation. It plays a significant role in solving crimes by helping to link offenders to their actions and victims. Proper handling of the physical evidence is critical, and all investigators and forensic experts must have a deep understanding of the science behind it. We encourage readers to stay informed and appreciate the value of properly collected, analyzed, and used physical evidence in crime investigations.
