Forensic Evidence Types to Know for Criminology

Forensic evidence plays a crucial role in criminology by linking suspects to crimes through scientific analysis. Various types, like DNA, fingerprints, and digital forensics, help investigators uncover the truth and build strong cases in the pursuit of justice.

1. DNA evidence

   • DNA profiling can uniquely identify individuals, making it a powerful tool in criminal investigations.
   • Samples can be collected from various sources, including blood, saliva, and skin cells.
   • The process involves comparing DNA from a crime scene to known samples, which can link suspects to the crime.

2. Fingerprints

   • Fingerprints are unique to each individual and remain unchanged throughout a person's life.
   • They can be collected from various surfaces using techniques like dusting or chemical fuming.
   • Automated fingerprint identification systems (AFIS) can quickly match prints to known individuals.

3. Trace evidence (hair, fibers, soil)

   • Trace evidence can provide crucial links between a suspect, victim, and crime scene.
   • Hair and fibers can be transferred during contact and can be analyzed for DNA or microscopic characteristics.
   • Soil samples can reveal geographic locations and help establish connections to a crime scene.

4. Ballistics and firearm evidence

   • Ballistics examines the behavior of projectiles and firearms, helping to determine the type of weapon used.
   • Firearm evidence includes bullet striations and cartridge casings, which can be matched to specific guns.
   • Gunshot residue analysis can indicate whether a suspect fired a weapon.

5. Blood spatter analysis

   • Blood spatter patterns can provide insights into the events surrounding a crime, such as the position of the victim and assailant.
   • Analysts study the size, shape, and distribution of blood droplets to reconstruct the sequence of events.
   • Different patterns can indicate the type of force used and the angle of impact.

6. Digital forensics

   • Digital forensics involves the recovery and investigation of material found in digital devices, such as computers and smartphones.
   • It can uncover evidence of criminal activity, including communications, files, and deleted data.
   • Techniques include data recovery, analysis of metadata, and network forensics.

7. Toxicology

   • Toxicology tests identify substances in a person's body, such as drugs, alcohol, and poisons.
   • It can help determine cause of death or impairment in cases of overdose or poisoning.
   • Samples can be taken from blood, urine, or tissues for analysis.

8. Footwear and tire impressions

   • Impressions can provide evidence of a suspect's presence at a crime scene and can be matched to specific footwear or vehicles.
   • The analysis includes examining tread patterns, size, and wear characteristics.
   • Casting techniques can preserve impressions for further examination.

9. Tool marks

   • Tool mark analysis examines impressions left by tools on surfaces, which can link tools to specific crimes.
   • Each tool leaves unique markings, allowing forensic experts to match marks to the tool used.
   • This evidence can be critical in burglary and assault cases.

10. Questioned documents

    • This field involves the analysis of handwriting, signatures, and printed materials to determine authenticity.
    • Experts examine ink, paper, and printing techniques to identify alterations or forgeries.
    • Document analysis can provide insights into the intent and authorship of written materials.