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Hair And Fiber analysis
Transcript of Hair And Fiber analysis
Shaquille Sinclair Differences between
Hair has three main parts:
•The Cuticle There are two main methods for examining hair patterns: Oblique Lighting can be used to determine
the scale pattern of a hair sample. The medullas of hairs also have specific patterns Hair Patterns Important Variables Examined Dyed hair The Methodology The Microspectrophotometer Microspectrophotometer in action Microspectrophotometer Usage What is it? •An instrument which is used to measure and analyze small samples in a non-destructive way
•Can measure the transmittance, absorbance, reflectance, polarization, fluorescence, and luminescence of a sample with UV (ultra-violet) or IR (infrared) •Collection of the textile fibers are critical
-Small fibers can be weighed as Trace Evidence, or resulting from contact
-Key to reconstructing the crime scene
•In the lab, fibers are examined under a multitude of microscopes
-Compound light microscope equipped with polarized light capability
•The fibers are then compared with known textile patterns to determine the characteristics of the fabric
•This information, compounded with facts from the crime scene, are used to establish links between suspects and the crime scene •Fiber type – microsopy can reveal what the fiber is made of, and can reveal hints as to how it was made
•Fiber colors – variety of dyes alond with a variety of application methods, can reveal the source of the fiber
•Number of Fibers – The number of fibers present can be used to determine the nature of contact at the scene. The greater the number, the more likely direct contact was involved.
•Fiber Location – Where exactly on the body that the fiber was found can be used to associate the fiber with a suspect or victim.
•Fabric Type – Different textiles shed fibers differently. The condition of the textile may also affect how many fibers get shredded or transferred.
•Multiple Fiber Association – Likelihood for contact increases if different sets of fibers seem to follow a trend in the crime scene. Hair dye, although visible on a macroscopic level, has great importance when viewed on a smaller scale. It affects the growth and the natural color and consistency of hair, making it a very indicative form of hair analysis. •By using Oblique lighting
•By using Direct Lighting The three scale patterns are Spinous, Coronal, and Imbricate.
•Spinous hair samples have a scale pattern similar to roof tiles; this pattern has been said to resemble spines.
•Coronal hair samples look similar to a stack of crowns.
•Imbricate hair samples look like an overlap of cell edges (these are the only scale patterns attributed to humans). The medulla can be examined by shining light directly through a hair sample. A medulla can be:
•Fragmented (broken at many points, either randomly or in a pattern)
•Absent (the medulla is either not present or extremely fragmented Hair analysis is often used in forensic studies, as it is sometimes the only way to identify victims or suspects in a crime. The studies often occur at a molecular level where the variety in hair structures increases. The variability in hair is at its peak in the hair from the scalp or from the pubic region, and are the most significant when doing hair analysis. This is useful in identifying rape culprits and distinguishing between them and the victims. While hair analysis is a reliable tool, it is not a 100 percent determiner of culpability, and is inadmissible in court. •It's used in identifying textile fibers, such as cotton, wool, nylon, or man-made synthetic products ( ie. umbrellas) as well as dyed hair
•In using UV and IR light rays, scientists can determine the nature and color of fibers
•By Analyzing hair, forensic scientist can determine the involvement of someone from a crime scene (eg: Drug use, nutrition, etc) The Importance of Fibers
•Different types of manufactured fibers have different patterns due to the way the machines weave the threads
•Fibers get shredded or picked up from daily activities
•Evaluating fibers can create a link between a suspect being at the scene of the crime Dye analysis can help to identify differences amongst people, to determine the role a person
played in a crime, or to help
judge hair damage/changes Mink Coronal Cuticle Scaling Racoon Flattened Cuticle Scaling Animal Hair vs. Human Hair Similarities
Composed of keratin and melanin pigment
Has roots, shafts, cuticles, medullas and cortexes
Cuticle Scaling (Coronal, Spinous, Flattened)
- Found on bats and some animals
- Rare in humans
- Found on cats, seals, and minks
- Never found on humans
- Found on some animals
- Most common on humans Properties Protective Nature
- Thinner than animal hair
- The medulla in our hair is 1/3 the width of a strand of hair
- The medulla is thicker than 1/3 the hair’s width
- Coloring is consistent from root to tip
- Melanin in the cortex is usually of consistent density
- Pigment may become more dense near the cuticle
- Coloring may change several times from root to tip (banding)
- Melanin in animal hair becomes more dense near the medulla Bibliography •"Under the Microscope: Get Forensic with Hair Analysis | Carolina.com." Science Supplies & Curriculum - STEM - Chemistry. Carolina Biological Supply Compan, n.d. Web. 15 Jan. 2013. <http://www.carolina.com/teacher-resources/Interactive/forensic-hair-analysis-activity/tr10879.tr>.
•"Hair « Crime Scene Investigation."Crime Scene Investigation. N.p., n.d. Web. 15 Jan. 2013. <http://hannahc12.wordpress.com/tag/hair
•"Raman for Forensic Science." CRAIC Technologies Mobile. CRAIC Technologies, n.d. Web. 15 Jan. 2013. <http://www.microspectra.com/component/content/article/40-solutions/295-raman-for-forensic-science>.
•"Forensic Human Hair Examination Guidelines ." Tool for SEO. N.p., n.d. Web. 15 Jan. 2013. <www.swgmat.org/Forensic%20Human%20H
•"Forensic Analysis of Trace Evidence with the QDI 2010 Forensic™ Microspectrometer | Biocompare.com."Biocompare | The Buyer's Guide For Life Scientists. Biocompare, n.d. Web. 15 Jan. 2013. <http://www.biocompare.com/Life-Science-News/47422-Forensic-Analysis-of-Trace-Evidence-with-the-QDI-2010-Forensic-Microspectrometer/>.
•Yirka, Bob. "New forensic laser technique for hair analysis can reveal historical data." Phys.org - Science News, Technology, Physics, Nanotechnology, Space Science, Earth Science, Medicine. Phys Org, n.d. Web. 15 Jan. 2013. <http://phys.org/news/2011-04-forensic-laser-technique-hair-analysis.html>.