Name: _________________________________________________________ Date: ____________

Fiber Make-up Lab

Directions: You will be comparing a crime scene sample to 5 standard reference samples. Through observation you will have to match and identify which standard reference sample matches the crime scene through microscopic cross sectional views of fibers as well as fiber burn-test analyses.

A crime has been committed and the female victim was found in her apartment with several red fibers left behind. The victim despised the color red and did not own anything that was red.

Below you will view the crime scene fiber.

Crime Scene Fiber: The following is a microscopic and cross-sectional view of the fiber found at a crime scene and on the female victim.

Along with the microscopic examination of the unknown fiber, a fiber-burn test was completed. The results of the burn test are as follows:

Fabric Approaching the flame

In flame Removed from flame

Odor Residue

Unknown No change Ignited like a wick, created dark yellow to orange flame

Continued to burn like a candle wick, until extinguished

Burning paper or leaves type odor

Grayish, fluffy, almost power-like

Use the following standard reference samples of cross sectional view an burn test table to narrow down and identify the type of fiber that was left behind.

Answer Analysis questions.

FABRIC FLAME QUALITY ODOR ASH QUALITY COMMMENTS

WOOL orange color, sputteryburning hair or feathers

blackish, turns to powder when crushed

flame will self-extinguish if flame source is removed, no smoke

SILK burns slowlyburning hair or feathers

grayish, turns to powder when crushed

burns more easily than wool but will self extinguish is flame source removed

COTTON yellow to orange color, steady flame

burning paper or leaves

grayish, fluffy slow burning ember

LINEN yellow to orange color, steady flame

burning paper or leaves

grayish, fluffytakes longer to ignite than cotton, but otherwise very similar

RAYON fast orange flameburning paper or leaves

almost no ashwill continue to burn after flame source removed

POLYESTER orange flame, sputterysweet or fruity smell

hard shiny black bead

black smoke

ACETATE burns and melts, sizzlyacidic or vinegary

hard black beadwill continue to burn after flame source removed

NYLONburns slowly and melts, bluse base and orange tip, no smoke

burning celery

hard grayish or brownish bead

will self extinguish if flame source removed

ACRYLIC burns and melts, white-orange tip, no smoke

acrid black hard crustwill continue to burn after flame source removed

Analysis questions:

1. From the cross-sectional analysis, what fiber most closely resembles the unknown fiber. Describe the characteristics they have in common.

2. From the burn test, what type of fiber is most similar to the unknown fiber taken from the victim? Describe the characteristics they have in common.

3. What overall fiber matched the crime scene fiber? Explain how you were able to identify the unknown fiber.

4. If you were the examiner on the case, list at least two other analyses or examinations you would complete on this fiber.

5. If you were the examiner on this case and you were called to testify about the fiber evidence. How confident are you in your prediction of the type of fiber you identified the unknown to be. Would you say you were 100% confident in your prediction? Why or why not?