1 / 23

Fingerprints

Fingerprints. History. 3000 years ago… Chinese used fingerprints for legal papers 1880 Henry Fauld –first to use FP to ID criminals 1897 Sir Edward Richard Henry- -developed Henry classification - based on all 10 prints - number/location of whorls. Skin.

aristotle-delgado
Download Presentation

Fingerprints

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fingerprints

  2. History • 3000 years ago… Chinese used fingerprints for legal papers • 1880 Henry Fauld –first to use FP to ID criminals • 1897 Sir Edward Richard Henry- -developed Henry classification - based on all 10 prints - number/location of whorls

  3. Skin • Epidermis- outer layer, no blood supply • Dermis-internal layer- sweat glands that produce water, salts, oils • Papillae- at boundary of dermis and epidermis Prints- made of mostly water, salts, oil

  4. Cross Section of Skin

  5. AFIS Automated Fingerprint Identification System

  6. Matching points Also known as: - Minutiae - Galton points Based on types of ridges Match ridges from a known print with an unknown print.

  7. Types of Ridges • Ending ridge • Bifurcation (fork) • Enclosure • Short ridge • Dot • Eye (island) • Bridge • Double bifurcation • Trifurcation

  8. Fingerprints • Friction ridges help human grip things • Identical twins have different fingerprints. • Fingerprints do not change over your lifetime. • Scarring, etc can be used for ID

  9. Deltas • Delta- ridge that diverges • Loops have one delta • Whorls have 2 deltas • Arches do not have deltas.

  10. Types of Fingerprints • 1. Arch • 2. Whorls • 3. Loops

  11. Arches Arches (no core or delta) • Plain • Tented

  12. Whorls • One or more ridges make complete circles • Two deltas and at least one core

  13. Loops • Radial- loop opens to thumb • Ulnar - loop opens to pinky side

  14. Pores • Found randomly along the ridges • Produce sweat • Chemicals in sweat make the fingerprint that is left behind • Pore location can be used to identify the person.

  15. Process of Identification Get prints of all ten fingers from a person in question (suspect, victims, police, etc..) Ways to get the 10 prints • Traditional ink and paper • Roll colorless chemical on treated paper… chemicals react and the print becomes visible (newer) • Live scan: roll prints on glass over video camera. Image is turned into digital information (newer)

  16. Quality of prints • Quality affected by: • Skill and experience of person taking the print • Cooperation of person giving the print • Damaged skin on people who work w/ their hands • Rigor mortis • Decomposition, burned bodies

  17. Types of Prints • 1. Visible (patent) • Bloody prints • 2. Plastic • Tacky paint • Putty • Clay • Soap • 3. Latent • Invisible • Deposit sweat and oil

  18. Methods to Develop Prints • Black powder • Magnetic powder • Iodine fuming (good on paper) • Silver nitrate • Ninhydrin ( for prints on paper) • Super glue (=cyanoacrylate) • Stickyside ™powder

  19. Locating prints • Shine flashlight at oblique angle • Gloves may leave impression • Less obvious places: under toilet seats, toilet handles, tabletops, dresser drawers, surface of dinner plates, back of rearview mirrors, trunk lids of cars • Use someone familiar w/ scene to tell if anything is different about the area

  20. Equipment • Ultraviolet light (black light) Some substances will glow when exposed to UV Ex. LSD– bluish-white Ex. Certain fingerprinting powders glow under UV • Laser • Alternate light source • powerful light causes some materials to fluoresce or luminesce

  21. Daubert Hearings • Fingerprint experts need to convince a judge that the methods used are valid. • Daubert standards: • Has the expert’s scientific method been tested? • Has the expert’s method been the subject of peer review and testing • What is the actual or potential rate of error? • do other scientists generally accept the expert’s methods?

  22. Odds and Ends • If AFIS is used to locate a match, the final identification must be done by a human • Palm prints can also be used • Latent prints can often be developed years later as long as they don’t become wet • Fingerprints made from soot, insulation, face powder are easily destroyed • Prints made from blood, ink, oil can last longer

More Related