Fingerprinting (latent)

1. Fingerprinting (latent) Biotechnology II

2. Skin Layers • Epidermis: superficial layers of keratinized stratified squamous epithelium

3. Layers • Dermis: deeper than epidermis; sheet of irregular fibrous dense connective tissue • Responsible for most of the structural strength • Blood vessels supply dermis and epidermis • Contains sensory nerve endings which are responsible for sensations such as hot and cold

4. Layers: Dermis continued • Papillary layer: bumpy superficial portion of dermis attached to the epidermis. • Papillae form regular rows in thick skin but are irregularly arranged in thin skin. This is why fingerprints and the soles of your feet have distinct ridges. These ridges also help with our ability to grip things.

5. Structure of Skin Did you know… stretch marks develop from a rupture in the dermis and the epidermis is not effected.

6. Hair • Did you know… • Hair is present on all skin surfaces except the palms, soles, lips, etc. • Hair follicle extends from surface into the dermis and contains a hair root • Hair shaft protrudes above the surface of the skin

7. Fingerprints • History • Japanese used thumb print as a signature on documents until 1860. • First used in crime in 1901 by Sir Edward Richard Henry • 3 Patterns • Whorl • Loop • Arch

8. Fingerprints • Most natural finger prints consists of secretions of the skin’s glands • 3 Glands • Eccrine: secretes H20 and inorganic & organic contaminants • Sebaceous: secretes fatty acids and hydrocarbons • Apocrine: secrete cytoplasm and nuclear materials such as carbohydrates

9. Fingerprints: Interesting Facts • Fingerprints are completely formed before birth • Genes determine finger prints but there can be slight differences between identical twins due to slight movement during development. • Yes, you can burn them off with acid BUT they will reform in exactly the same pattern you were born with • Ridge pattern never changes even as you get older.

10. Latent fingerprints • Fingerprints left behind at a crime scene • May or may not be visible • Visible usually have blood, grease, dirt, etc. in them to display the background • Non visible need treatment “latent print development” to be seen

11. Methods of Detection • Types of prints • Latent print • Visible print – deposited ink, blood, dirt • Plastic print – impression in a soft surface • Locating prints – RUVIS

12. Categories of Fingerprints • Loop – ridge lines enter one side of pattern and curve around to exit from the same side of pattern. (65%) • Ulnar loop – opens toward little finger • Radial loop – opens toward thumb Ulnar Loop Radial Loop

13. Categories of Fingerprints • Whorl – ridge lines rounded or circular and have two deltas(30-35%) • Plain whorl • Central pocket loop • Double loop • Accidental loop

14. Categories of Fingerprints • Arch – ridge lines enter print from one side and exit from the other (5%) • Plain • Tented

15. Developing Prints • Powders • Charcoal • Magnetic • Fluorescent • Chemicals • Iodine fuming (sublimation) • Ninhydrin • Physical developer (silver nitrate) • Super Glue fuming • Alternate Light Sources/ LED

16. Preservation of Developed Prints • Photographs • Print surface should be removed in its entirety (covered with cellophane) • Lifted from surface with tape • Digital imaging into pixels – allows adjustments to be made to enhance picture

17. Classification of Fingerprints • Henry system – numerical system involving the presence or absence of the whorl pattern on each finger as part of the primary classification.. • This does not identify someone, only reduce the number of possible candidates • AFIS – 10 print system that can search 500,000 stored ten-prints in 0.8 seconds • Data entered now by Livescan rather than ink rolling. • Human decisions must still be made • Software incompatibilities among states