Chapter 4
Fiber Analysis
Fiber Analysis
Below you will find case studies and case file activities students may complete at the end of the chapter. I have included the "Scenario" statements provided in the student textbook for each activity. For cases that do not list a "Scenario" or for scenarios that are extensive, I have provided a description of objectives instead. These "Case Files" will be used to guide each chapter.
Students will engage in many other activities provided by the textbook resource and they will access all activities through the Schoology platform.
Forensic Science Investigation Activities
A murder victim was discovered along a roadside. Police recovered carpet samples from the victim’s body. It is speculated that the victim was brought to the location using a car belonging to one of the suspects. Some of the carpet fibers from the floor of the car were transferred to the victim’s body. Your task is to determine if the carpet fiber found on the victim’s body is consistent with one of the carpet fibers taken from the cars of four different suspects.
Weave patterns can help identify a fabric associated with a crime scene. In this lab, you are investigating an assault in which the victim tore off and saved a piece of his attacker’s shirt. Five suspects were taken in for questioning. The judge issued a warrant to search the suspects’ homes for the torn shirt obtained during the assault. Your task will be to examine each of the suspects’ shirts and determine if any of the fabrics are consistent with the torn shirt from the crime scene.
A robbery occurred within a well-to-do neighborhood. The thief grabbed an expensive satin-weave, cream-colored pillowcase to carry out the jewelry that he stole from the jewelry box in the bedroom. The thief immediately took the jewels to a nearby pawnshop to exchange the jewels for money. He then tossed the pillowcase onto the backseat of his car. Later that evening, the police were able to get a description of the thief from the pawnshop owner.
Feeling elated at having gotten so much money for the stolen goods, the thief and some of his friends celebrated at the local bar. Having had too much alcohol, the thief was driving erratically on his way home. The police stopped the man to give him a ticket for DWI and noticed the cream-colored pillowcase in the back of his car. The policeman recalled the earlier message sent to all officers regarding the home jewelry thief and the missing pillowcase and brought the man in for questioning. Later that evening, two other men matching the pawnshop owner’s description were also brought in for questioning. Police removed similar cream-colored pillowcases at their homes to be examined by the crime lab.
Were any of these pillowcases taken from the home where the robbery occurred? Was it a satin-weave? Was the color the same? Because many people purchase cream-colored pillowcases, what other characteristics would the forensic examiner use to compare this pillowcase with the other pillowcases found on the bed where the incident occurred?
In this activity, you will examine textile samples and use characteristics such as weave pattern and number of threads to help compare a fabric from a crime scene with fabric evidence found on the three suspects.
By the end of this investigation you will be able to: Distinguish among textiles based on weave patterns, thread counts, and microscopic fiber analyses.
Apply knowledge of textile characteristics to a forensic science problem.
Prepare an expert witness testimony based on the scientific evidence.
Carpet fibers were found on the victim at the crime scene. It is speculated that the victim was transported in one of the suspect’s cars. According to Locard’s Principle of Exchange, some of the fibers were transferred from the car to the victim’s body. Determine if the carpet sample found on the victim’s body is consistent with one of the carpet samples taken from a suspect’s car.
Bertino, A. J., & Bertino, P. (2020). Forensic Science: Fundamentals & Investigations (Forensic Science, Fundamentals and Investigations) (3rd ed.). Cengage Learning.