Tool Marks, Questioned Documents, and Biological Evidence

Forensic science utilizes various types of evidence in forensic science to solve crimes, including tool marks, questioned documents, and biological samples. These pieces of evidence provide crucial information that can link suspects to crime scenes and help investigators reconstruct events.

Tool Marks: As tools are used, tiny nicks and chips form on their edges, creating unique patterns that can be used to identify matches between evidence and suspects. Tools may also pick up traces of blood or other substances that can be tested, or have fingerprints that can be lifted.

Questioned Documents: Document examiners analyze items such as ransom notes or other suspicious documents to find clues linking them to a crime scene or specific suspect. They examine:

• Type of paper used
• Printing method
• Handwriting style
• Type of ink
• Unique features like watermarks or indentations

Example: Indentations made as someone wrote on a page in a notebook can provide useful clues about the document's origin or content.

Serology and DNA Evidence: Biological evidence such as blood, semen, saliva, sweat, and urine can provide valuable information about a crime, its victim, or suspects.

Vocabulary: CODIS (Combined DNA Index System) - A database maintained by the FBI used to find matches to unknown DNA samples from crime scenes.

Key points about biological evidence collection and analysis:

1. Chemicals and ultraviolet light are used at crime scenes to locate body fluid evidence.
2. Potential evidence areas are swabbed, bagged, and collected in airtight vials to prevent cross-contamination.
3. DNA can be extracted from various tissues, including hair, fingernails, bones, and teeth.
4. DNA profiles created from evidence can be compared to profiles from suspects or victims.

Highlight: The use of DNA evidence and databases like CODIS has revolutionized forensic science, allowing for the identification of suspects and the resolution of cold cases.

Skeletal Remains and Forensic Anthropology

Forensic anthropology is a specialized field within forensic science that focuses on the analysis of skeletal remains. This discipline plays a crucial role in identifying victims, determining cause of death, and providing valuable information in criminal investigations.

Forensic anthropologists analyze skeletal remains to determine four key characteristics:

1. Age at death
2. Sex
3. Ancestry
4. Stature (height)

Definition: Forensic Anthropology - The application of physical anthropology techniques to legal cases, particularly in the identification and analysis of human skeletal remains.

These experts use various methods to extract information from bones, including:

• Morphological analysis: Examining the shape and structure of bones
• Metric analysis: Taking precise measurements of bones
• Microscopic examination: Looking at bone tissue under high magnification
• Chemical analysis: Studying the composition of bones for additional clues

Highlight: Forensic anthropology is particularly valuable in cases involving decomposed or skeletonized remains, where traditional identification methods may not be applicable.

The information gathered by forensic anthropologists can help:

• Identify unknown victims
• Estimate time since death
• Determine circumstances surrounding death
• Provide evidence of trauma or pathological conditions

Example: In a case involving unidentified skeletal remains, a forensic anthropologist might determine that the victim was a male in his mid-30s, approximately 5'10" tall, and of European ancestry, narrowing down the pool of potential missing persons.

By combining their expertise with other forensic disciplines, such as DNA analysis and forensic odontology, forensic anthropologists contribute significantly to the resolution of complex criminal cases and the identification of missing persons.

Explosives and Ballistics Evidence

Forensic analysis of explosives and firearms plays a critical role in solving crimes involving these dangerous materials. These types of evidence in forensic science provide valuable insights into the nature of the crime and help identify potential suspects.

Explosives analysis involves determining the chemical composition of explosive substances to identify their type and origin. Trace evidence of explosives can be found on a suspect's clothing, skin, hair, or other objects and matched to explosives from a crime scene. Additionally, materials used to construct explosive devices are compared to evidence found in a suspect's possession to confirm a match.

Vocabulary: Gunshot Residue (GSR) - Particles expelled when a firearm is discharged, which can be detected on a person's hands, face, or clothing.

Ballistics evidence examination focuses on the characteristics of ammunition, firearms, and residue. Key aspects of ballistics analysis include:

1. Chemical tests to reveal gunshot residue (GSR) on hands, face, or clothing
2. Examination of rifling marks on fired bullets to match them to specific weapons
3. Use of the Integrated Ballistics Identification System (IBIS) database to compare markings from ballistic evidence

Highlight: The analysis of gunshot residue in forensic investigation can indicate how close a person was to a fired gun, providing crucial information about their involvement in a shooting incident.

Dust and dirt evidence can also reveal valuable information about a person's movements or connections to a crime scene. Investigators examine samples for chemical composition, pollen, plant material, and organic matter to establish links to specific locations.