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Forensic Science - 03 Fibres and fabrics
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Forensic Science - 03 Fibres and fabrics

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A closer look at how forensic scientists investigate fibres and fabrics as part of a criminal investigation for Year 9 students at Saint Ignatius College Geelong.

A closer look at how forensic scientists investigate fibres and fabrics as part of a criminal investigation for Year 9 students at Saint Ignatius College Geelong.

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Forensic Science - 03 Fibres and fabrics Forensic Science - 03 Fibres and fabrics Presentation Transcript

  • DRYSDALE CSI Fibres and fabrics. Ian Anderson Saint Ignatius College Geelong
  •  When we wear clothes, walk on carpet, sit on the lounge or pull on a jumper, fibres either fall off or are picked up. WHY FIBRES? Source: http://blog.stylewithcindy.com.au/boxing-day-sales-tips/
  •  Fibres are used in forensic science to create a link between crime and suspect.  Fibres are a form of trace evidence.  Direct transfer = fibres are transferred directly from victim to suspect or from suspect to victim.  Secondary transfer = the victim has picked up fibres and then transferred them to the suspect.  Most common form of fibre transfer is shedding of textile.  e.g. clothing, carpets and upholstery. WHY FIBRES?
  •  Forensic scientists will try to determine  The type of a fibre.  It’s colour.  How many fibres of each kind were found.  Where they were found.  What textile the fibre came from.  Whether there were transfers of multiple types of fibres. HOW FORENSIC SCIENTISTS USE FIBRES. Source: http://www.exploreforensics.co.uk
  •  The value of fibre evidence is dependent upon its potential uniqueness. HOW FORENSIC SCIENTISTS USE FIBRES. Source: http://www.tumblr.com/tagged/pink%20everything
  •  Fibres are classified as either natural or synthetic. FIBRE CLASSIFICATION. Source: http://www.modernhometoday.com/natural-vs-synthetic-furniture-fabric- advantages-disadvantages/
  • NATURAL FIBRES. Come from animals, plants and minerals mined from the ground.  Animal fibres.  Hair (e.g. wool, cashmere, mohair, angora).  Fur (e.g. sheep, fox).  Silk. Source: http://martybugs.net/gallery/?gal=200712Busselton &img=IMG_11013
  • NATURAL FIBRES.  Plant fibres.  Seed fibres (e.g. cotton).  Fruit fibres (e.g. coir from coconuts).  Stem fibres (e.g. hemp, jute and flax).  Flax = linen.  Leaf fibres (e.g. sisal and manila).  Mineral fibres.  e.g. fibreglass and asbestos. Source: http://cottonaustralia.com.au/cotton- library/video
  • SYNTHETIC FIBRES.  Categorized as polymers and regenerated fibres.  Over half of fibres produced today are synthetic fibres.  Synthetic polymer fibres.  Petroleum products.  Include polyester, nylon and acrylic.  Regenerated fibres.  Are mostly plant in origin and are derived from cellulose.  Include rayon. Source: http://www.funkyflytying.co.uk
  •  Synthetic fibres are stronger than the strongest natural fibres!  Unlike natural fibres, synthetic fibres are not damaged by microorganisms.  Synthetic fibres melt at a lower temperatures compared to natural fibres.  Unlike natural fibres, synthetic fibres can be damaged by sunlight NATURAL V SYNTHETIC FIBRES
  • NATURAL V SYNTHETIC FIBRES  Under the microscope.
  • NATURAL V SYNTHETIC FIBRES  Under the microscope. Source: http://luthvarian.blogspot.com.au
  •  Fibres too short in their raw state to be used as textiles may be spun together to make yarns.  For example, cotton fibres are only up to 5cm in length and must be spun together to form a very strong yarn.  Wool is also spun together to make a yarn.  Synthetic fibres can also be spun into yarns. YARNS Source: Bertino 2012
  •  Fibres can be woven into textiles or fabrics.  There are many different types of weave patterns.  e.g. tabby, twill and satin.  Textiles will also differ in their thread count.  e.g. bedsheets can be 180, 300 or 500 threads per inch. TEXTILES Plain weave Satin weave Source: Bertino 2012 Source: Bertino 2012
  • CASE STUDY Roger Payne (1968).  Bernard Josephs arrived home to find his wife dead. She had been wearing a purplish-red (cerise) woollen dress. On examination, it was determined that Claire Josephs had been choked into unconsciousness and then had her throat cut with a serrated knife. There was no forcible entry, and Claire appeared to have been in the middle of cooking. This indicated to the police that the murderer was probably someone Claire knew. Source: Bertino 2012
  • CASE STUDY Roger Payne (1962).  Suspicion fell to an acquaintance named Roger Payne. On examination of his clothing, more than 60 of the unusual cerise coloured fibres were found. These fibres led to the further examination of Payne’s clothing, and fibres from a red scarf similar to Payne’s were found under Claire’s thumbnail. Additional evidence led to the conviction of Payne and the sentence of life imprisonment.
  • CASE STUDY Amanda Davies (1992). A woman was found knifed to death under a bridge. She was wearing a blue- and-gray acrylic sweater. There were no fingerprints, no witnesses, and no weapon. She had recently returned from a vacation and had some photographs of herself in some provocative poses with strange people. On the night she died, she told her parents she was going to see her boyfriend and show him the pictures to "rekindle his interest." After the body was found, her boyfriend was interviewed. He said that he had seen her and that she had been in his truck, but that he had dropped her off "downtown." After obtaining a search warrant, investigators searched his truck and found a yellow polyester blanket. When the crime laboratory examined the sweater, they found about 40 yellow polyester fibers similar to those from the blanket. Likewise, examination of the blanket revealed more than 30 blue and gray acrylic fibers that matched the sweater. No attempts were made to determine how readily the sweater or blanket shed fibers or how well foreign fibers adhered to these textiles. It would not have been proper to put the actual articles in contact with each other, but the defense argued that similar garments could have been used to investigate the "sheddability" of the garments.
  • CASE STUDY Amanda Davies (1992). At the trial the prosecutor tried to establish that there was a "primary transfer" between the blanket and the sweater and that the large number of fibers mutually transferred showed that the transfer had been recent. In other words, the prosecutor argued that the blanket had been in direct contact with the victim's sweater right before she died. Because the blanket was found in the truck, this implied that she had been in the truck shortly before she died. This was virtually the only physical evidence available during the case. The other circumstances, such as those shown in the photographs, were used to establish a motive. The defense argued that the number of fibers transferred may or may not indicate a primary transfer. If these garments shed easily, the victim could have deposited fibers from her sweater into the suspect's truck on a previous occasion. Because the accused kept the blanket in the truck at all times, sometimes in the front seat, the defense argued that the sweater could have picked up blanket fibers from the truck seat; in other words, the truck seat could have acted as an intermediary for a secondary transfer of fibers. Because the crime lab had not done any testing to determine how easily these garments shed, the prosecutor could not know if the 30 to 40 fibers was a "large number." Faced with these arguments, the jury returned a verdict of "not guilty."
  • Bertino, A.J. (2012). Forensic Science: Fundamentals and investigations. Melbourne: Cengage Learning. BIBLIOGRAPHY.
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