Trace and Materials Evidence

Sample Solution

Combustibles and Explosives Evidence Description Combustibles and explosives evidence is any physical evidence that is related to the use of fire or explosives. This type of evidence can include a wide variety of items, such as:

• Accelerants: Substances that are used to start or spread a fire, such as gasoline, kerosene, and lighter fluid.
• Explosives: Substances that undergo a rapid chemical reaction to produce heat and gas, such as dynamite, TNT, and C4.
• Explosives residues: Microscopic particles of explosives or explosive devices that can be found on clothing, skin, and other objects.
• Fire debris: The charred remains of objects that have been burned, such as wood, paper, and textiles.
• Bomb components: Parts of bombs or explosives devices, such as detonators, timers, and switches.

Overview The use of fire and explosives as tools for crime has been around for centuries. However, the scientific study of combustibles and explosives evidence is a relatively recent development. The first major breakthrough in the field of explosives analysis came in the late 19th century, when Austrian chemist Edmund R. von Hofmann developed a test for detecting nitroglycerin, a common ingredient in explosives at the time. This test, known as the Hofmann test, is still used today by forensic scientists to identify explosives residues. Another major breakthrough came in the early 20th century, when American chemist William R. Brode developed a method for detecting gasoline and other petroleum products at crime scenes. This method, known as the Brode test, is also still used today by forensic scientists. Historical Significance Combustibles and explosives evidence has been used to solve countless crimes over the years. Some notable examples include:

• The 1921 Wall Street bombing: Forensic scientists used evidence of explosives residues to identify the perpetrators of this bombing, which killed 38 people and injured hundreds more.
• The 1995 Oklahoma City bombing: Forensic scientists used evidence of explosives residues and bomb components to identify the perpetrators of this bombing, which killed 168 people and injured hundreds more.
• The 2001 World Trade Center attacks: Forensic scientists used evidence of explosives residues and bomb components to identify the perpetrators of these attacks, which killed nearly 3,000 people.

Current Uses Combustibles and explosives evidence is used in a variety of forensic investigations today, including:

• Fire investigations: Forensic scientists can use combustibles and explosives evidence to determine the cause and origin of a fire, and to identify any accelerants that may have been used.
• Bombing investigations: Forensic scientists can use combustibles and explosives evidence to identify the type of explosive used in a bombing, and to track down the perpetrators of the bombing.
• Arson investigations: Forensic scientists can use combustibles and explosives evidence to determine whether a fire was intentionally set, and to identify any accelerants that may have been used.

Documentation Combustibles and explosives evidence must be carefully documented at the crime scene. This includes taking photographs and videos of the evidence, as well as collecting samples of the evidence for analysis in the laboratory. Packaging Combustibles and explosives evidence must be packaged in a way that will prevent it from being contaminated or damaged. This typically involves packaging the evidence in airtight containers and labeling the containers clearly. Methodology The methodology used to collect and analyze combustibles and explosives evidence is constantly evolving. However, some common methods include:

• Gas chromatography-mass spectrometry (GC-MS): GC-MS is a technique that is used to separate and identify the components of a mixture. GC-MS is often used to identify explosives residues and accelerants.
• High-performance liquid chromatography (HPLC): HPLC is a technique that is used to separate and identify the components of a mixture based on their polarity. HPLC is often used to identify explosives residues and accelerants.
• Fourier transform infrared spectroscopy (FTIR): FTIR is a technique that is used to identify the chemical structure of a substance. FTIR is often used to identify explosives residues and accelerants.

Admissibility Issues Combustibles and explosives evidence is generally admissible in court. However, there are some exceptions to this rule. For example, evidence that has been collected in violation of the defendant's constitutional rights may not be admissible in court. Additionally, evidence that is not relevant to the case may not be admissible in court. Conclusion Combustibles and explosives evidence is a valuable tool for forensic scientists. This type of evidence can be used to solve a wide variety of crimes, including arson, bombings, and homicides. Forensic scientists use a variety of scientific methods to collect, analyze, and document combustibles and explosives evidence. Combustibles and explosives evidence