Both natural and synthetic fibers often provide a form of trace evidence that can be used in forensic science and criminal investigations. When pieces of material transfer from one person or object to another, it often results in this type of fiber evidence. In criminal cases, the transfer of fibers from the perpetrator to the victim can sometimes lead to an arrest. Fiber evidence typically cannot lead to a positive identification because fibers are not unique to one person in the same way that fingerprints or genetic samples are. In this way, fiber evidence is often useful to link a person of interest to a crime even though other evidence typically must be obtained for any criminal charges to be successful.
Trace evidence is often instrumental in building a criminal case or establishing a course of events. Any time that two objects come into contact, trace evidence may be left. These substances can be used to trace the movement of an object or contact between people. Tire tracks are one form of trace evidence that can be used to establish the course of events that transpired during a traffic accident. Fiber evidence is another form that can be used to determine whether two people came into contact with one another or if a person was in a certain location.
Many different items can leave fiber evidence. Fibers are simply thin filaments of material that can be either organic or synthetic. Natural fibers include vegetable matter, such as cotton and hemp, and animal products, such as wool and fur, while man made and synthetic fibers include materials such as fiberglass and rayon. Human hair is technically a fiber, though it is often treated differently since it contains valuable deoxyribonucleic acid (DNA) evidence. Many of these materials can transfer easily from one surface to another, which makes them an excellent source of trace evidence.
Even though fibers are not unique in the same way as fingerprints and genetic evidence, each type of fiber can be identified through forensic science. This can allow fiber evidence from one crime to be linked to another, which may allow other evidence from the previously unrelated cases to be combined. Another common use of fiber evidence is to connect a person of interest to a crime. After a suspect has been identified in this way, additional evidence may be gathered. Fibers usually are not used alone, though they can be an essential form of supporting evidence.