Forensic Science
T. Trimpe 2007 http://sciencespot.net/
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Fingerprint Analysis: Collecting and Developing Latent Prints, Slides of Forensics
An overview of fingerprint analysis, focusing on the collection and development of latent prints. It covers various types of prints, including visible, plastic, and latent prints, and the methods used to reveal and lift them. The document also mentions the use of different powders, such as black powder, magnetic powder, and cyanoacrylate fuming, as well as chemicals like iodine and ninhydrin. Students will learn how to properly collect and develop fingerprints for forensic analysis.
Typology: Slides
2012/2013
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Forensic Science
T. Trimpe 2007 http://sciencespot.net/ Docsity.com
Fingerprints
• Visible prints are made after
coming in contact with colored
material such as blood, paint,
grease, or ink.
• Plastic prints are ridge
impressions left on a soft
material such as putty, wax,
soap, or dust. bsapp.com Docsity.com
• Latent prints (invisible prints)
are caused by the transfer of
body perspiration or oils
present on the finger to the
surface of an object.
• Latent prints must be
developed or made visible
Fingerprints
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bsapp.combsapp.com Docsity.com
Remove Excess Dust
Brush or Blow
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Use Tape to Lift the Print
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The cyanoacrylate fuming method (often called the super glue method) is a procedure that is used to develop latent fingerprints on a variety of objects.
Bottom Right: http://www.forensicsrus.com/images/SupergluePrint.jpg
Magnetic powder can also be used to reveal latent prints. This type of powder works better on shiny surfaces or plastic baggies or containers.
Top Left: http://www.stapletonandassociates.com/images/MagPowder.jpg Bottom Left: http://www.ok.gov/osbi/images/ninhydrin%20print.jpg
Click the icon to view the Crime 360 Super Glue Video
Some investigators use fluorescent powder and UV lights to help them find latent prints on multi-colored or dark surfaces.
Ninhydrin is a chemical that bonds with the amino acids in fingerprints and will produce a blue or purple color. It is used to lift prints from surfaces such as paper and cardboard.
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Iodine Fuming
• Appropriate Surface:
– porous and non-porous such
as paper, index cards,
magazines, and cardboard.
• Theory:
– Sweat and oil will absorb
iodine vapors
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Print Should Develop in a
Few Minutes
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Soak Suspected Surface with
Ninhydrin Solution & Allow to
Dry bsapp.com Docsity.com
Directions:
1 - Cover your table with white butcher paper or newspaper. You must dust everything on the paper!
2 - Get a lifting kit from your teacher that contains black powder, brushes, and clear tape.
3 - Press the pad of your right thumb on a CD or glass slide to make a print. Place on the paper covering your table.
4 – Dip a brush lightly into the container of black powder and then tap off the extra on the lid. You only need a very small amount of powder to dust the print.
5 – Hold the brush over the print and rotate it between your thumb and fingers. Use the brush to remove any extra powder.
6 - Use a small piece of clear tape to lift the print and place it in the box on your worksheet.
CAUTION: The black powder will be messy and isn’t easy to clean up. Don’t dust anything without permission!
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Clean Up
1 – Clean off the CDs or glass slides and put them back in the kit
with the brushes and tape.
2 – Have someone help you fold the paper in half and tap it to return
the extra black powder to the container.
3 – Put the black powder in the box and have it checked in by your
teacher.
4 – Get a towel and “dry” wash the table – especially the edges that
weren’t covered with paper.
5 – Get a wet towel to wash off the table and then wipe it with some
dry towels. Keep cleaning until all the black powder is off the table!
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