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  • CasTips07 – Casting With Polyvinylsiloxane

    By: Administrator
    Polyvinylsiloxane (PVS) differs from the many silicone-based toolmark recovery methods in that it uses equal parts of base material and catalyst. Most of us who have used Mikrosil or Durocast have messed up casts because we used too little or too much catalyst when mixing PVS Casting Kit the material. But the guesswork is eliminated when using PVS because of its unique delivery system. By Don Penven Over the years I have worked with virtually every crime scene casting medium available. My...
  • CasTips06 – Casting in Standing Water

    By: Administrator
    How often have you encountered footprints or tire tracks at the bottom of a puddle? Granted, this doesn’t happen often but when it does—desperate measures are needed to recover those impressions. By Don Penven How often have you encountered footprints or tire tracks at the bottom of a puddle? Granted, this doesn’t happen often but when it does—desperate measures are needed to recover those impressions. Most liquid silicone formulations will just float on top of the water’s surface....
  • CasTips05 – Toolmark-Bite Mark Recovery

    By: Administrator
    Toolmarks are frequently apparent at points of entry occurring during a burglary, but this form of impression evidence covers a number of other 3-dimensional impressions uncovered at crime scenes—most notably—bites marks. By: Don Penven Recovering toolmark impression evidence can be a valuable contribution toward successful prosecutions—if it is done properly. Toolmarks are frequently apparent at points of entry occurring during a burglary, but this form of impression evidence covers a...
  • CasTips04 Tire and Footprint Casting Techniques

    By: Administrator
    Two different materials have been popular for the collection of 3-D impressions in soil, sand and snow: plaster-of-paris (POP) and dental stone. By: Don Penven Two different materials have been popular for the collection of 3-D impressions in soil, sand and snow: plaster-of-paris (POP) and dental stone. POP was the medium of choice until sometime in the early 1990s. POP began to fall out of favor for several reasons; here are just a few: Compared to dental stone, POP has a slight shrinkage...
  • CasTips03 – Recovering Dust Impressions

    By: Administrator
    Dust impressions are fragile at best, so the utmost care must be taken when attempting to lift them. Some methods work better than others By: Don Penven Methods for Lifting Dust Print Impressions Dust impressions are fragile at best, so the utmost care must be taken when attempting to lift them. Some methods work better than others, so it is suggested that you make several trial runs before going after the real thing. Using adhesive materials to lift dust prints. Prior to the invention of the...
  • CasTips02 –Recording Dust Print Impressions

    By: Administrator
    The search for dust impressions must begin prior to any other activity except for rendering aid to injured persons. Crime Scene Investigation-- The Recording Dust Print Impressions By: Don Penven Dust prints occur at crime scenes as a result of two influences: They are tracked into a structure as a result of dust, dirt, pollen or other foreign material adhering to the soles of shoes Once inside the subject may walk through a dust covered area and will leave negative impressions—where the...
  • CasTips01 – Introduction to Impression Evidence

    By: Administrator
    Casting is the accepted term used at crime scenes and it refers to making casts of 3-dimensional evidence like toolmarks, footprints and tire tracks. By: Don Penven An Introduction to Impression Evidence It’s been more years than I can remember when I first heard the term “Moulage.” It was an old detective movie and one of the officers at a crime scene suggested making a moulage of footprints near a body. We certainly don’t hear this term used much anymore. Moulage in French means...