Forensic Science and Crime Scene Investigation

• Forensic science applies scientific principles and techniques to legal matters.
• This includes collecting, preserving, and analyzing physical evidence. The eventual aim is to uncover facts admissible in legal proceedings.
• Forensic scientists work both in laboratories and at crime scenes.
• They provide impartial scientific evidence for use in courts, supporting either the prosecution or defense in criminal and civil investigations.

Crime Scene Investigation

• Crime scene investigation involves securing and protecting the scene to maintain its integrity. Another aspect is documenting its condition and collecting physical evidence.
• The primary goals are to preserve the integrity of the scene. Make sure relevant evidence is identified, collected, and properly documented.
• First responders' actions at a crime scene are critical and can significantly impact the integrity of the evidence.
• Documentation incorporates detailed photography, sketching, and note-taking. These provide a comprehensive record of the scene.
• Evidence collection adheres to established protocols. These prevent contamination and ensure chain of custody.
• Chain of custody refers to the chronological documentation or paper trail. This tracks the seizure, custody, control, transfer, analysis, and disposition of physical or electronic evidence.
• Crime scene investigators employ various search techniques. Examples include grid searches, spiral searches, and zone searches, used to systematically examine the scene.
• Analysis of crime scene patterns can give valuable insights into the events that transpired.
• Crime scene reconstruction uses scientific methods, physical evidence, deductive reasoning, and their interrelationships. This helps to gain explicit knowledge of the series of events surrounding the commission of a crime.

Toxicology

• Forensic toxicology involves detecting and identifying drugs and poisons in biological samples (e.g., blood, urine, tissue).
• Toxicologists analyze samples to determine the presence, concentration, and effects of substances that may have contributed to a crime or death.
• Standard analyses include blood alcohol content (BAC) testing, drug screening, and identification of toxins.
• Forensic toxicologists also investigate drug-facilitated crimes like sexual assault or driving under the influence.
• They provide expert testimony in court related to their findings and the potential effects of the substances found.
• The study of toxicology includes understanding the absorption, distribution, metabolism, and excretion (ADME) of drugs and toxins in the body.
• Analytical techniques such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) are employed to identify and quantify substances.

Forensic Biology

• Forensic biology focuses on analyzing biological evidence, such as blood, semen, saliva, and hair samples.
• DNA analysis is a key component used to identify individuals. It can also link them to a crime scene or a victim.
• Serology involves examining body fluids to identify and characterize them.
• Forensic biologists perform bloodstain pattern analysis to reconstruct events that occurred at a crime scene.
• Analysis of skeletal remains (forensic anthropology) can provide information about identity, age, sex, and cause of death.
• Forensic botany and palynology (the study of pollen and spores) can provide information about the location of a crime. They can also reveal information about the movement of individuals or objects.
• Mitochondrial DNA analysis can be used when nuclear DNA is degraded or limited. It is more abundant and inherited maternally.

Digital Forensics

• Digital forensics involves identifying, collecting, preserving, analyzing, and reporting digital evidence.
• Digital evidence can be found on computers, smartphones, tablets, and other electronic devices.
• The goal is to recover data relevant to a legal case while maintaining its integrity.
• Digital forensic investigators use specialized tools and techniques to extract and analyze data from digital devices.
• Typical tasks include recovering deleted files, analyzing network traffic, and examining metadata.
• Chain of custody is critical to ensure the admissibility of digital evidence in court.
• Digital forensics also involves investigating cybercrimes, such as hacking, fraud, and identity theft.
• Mobile forensics focuses specifically on the extraction and analysis of data from mobile devices.
• Network forensics involves monitoring and analyzing network traffic to identify security breaches and other malicious activity.

Trace Evidence Analysis

• Trace evidence analysis involves the examination and comparison of small or microscopic materials. These materials may link a suspect to a crime scene or a victim.
• Common types of trace evidence include hair, fibers, paint, glass, soil, and gunshot residue (GSR).
• Microscopic analysis identifies and compares the characteristics of trace evidence samples.
• Spectroscopic techniques, like Fourier transform infrared (FTIR) spectroscopy and energy-dispersive X-ray spectroscopy (EDS), identify the chemical composition of materials.
• Hair analysis compares the microscopic characteristics of hair samples to determine if they could have a common origin.
• Fiber analysis identifies the type of fiber and compares it to known sources.
• Soil analysis links a suspect or object to a particular location based on the composition of the soil.
• Glass analysis compares the physical and optical properties of glass fragments to determine if they originated from the same source.
• Gunshot residue (GSR) analysis detects and identifies GSR particles on a suspect's hands or clothing to determine if they may have fired a weapon.
• Locard's Exchange Principle states that whenever two objects come into contact, there is a transfer of material between them.