Fingerprinting

Aim Fingerprint 1a – What is a fingerprint?

Stupid Crime of the Day

• A man and his girlfriend were robbing a convenience store.

• While waiting for her boyfriend to finish getting the money, the woman noticed a contest entry form.

• Thinking it would be cool to win, she filled out the form, complete with her name, address, and phone number.

• A few hours later the police were at the couple's house to arrest them.

Fingerprints• Fingerprints are the small ridges

found on: – fingertips, fingers, and palms– toes and soles of feet

• Provide friction to walking or handling items

• Also known as papillary ridges • Are an INDIVIDUALIZING

characteristic

Skin Structure• The skin is mainly made up of two layers:• The outer layer - epidermis

• The cells in this layer provide protective, waterproof covering for the body

• The very top part of the epidermis is made up of dead cells (stratum corneum)

• The inner layer - dermis• made up of connective tissue• contains sweat glands, fatty

tissue, nerves, hair follicles, and oil glands.

Fingerprints are Individualizing:

1. Fingerprints never change over the course of your life

• From three months of gestation– Form as a result of blood

flow to baby and skin interaction with uterus

• Till putrification of the body after death– Breakdown of the skin by

bacterial action

Fingerprints are Individualizing:

2. Fingerprints are unique• There is a 1 in a trillion chance of

having the same fingerprints as someone else

• Identical twins = same DNA• But NOT the same fingerprints• Fingerprints ended use of bertillonage

after Case of the Two Will Wests (no relation to Kanye)

Fingerprints are Individualizing

3. Fingerprints can be categorized and filed

• Like snowflakes, no two prints are the same

• But, like snowflakes (90 different types of snowflake)

• they can be grouped or classified

• Modern labs use the AFIS or Automated Fingerprint Identification System to file fingerprints

Fingerprint Patterns• Fingerprints fall into three groups• Each group has the same general characteristics

– ARCH - 5% of all prints– LOOP - 60% of all prints– WHORL - 35% of all prints

• The patterns may be further divided into sub-groups– Arches = plain or tented– Loops = ulnar or radial– Whorls = plain, double loop,

central pocket loop, and accidental

Arches

• Plain arches – have smooth ridges– Slight shifting up and then down of papillary ridges

• Tented arches– Have sharp upthrusting ridge resembling tent poles

in the center of the print– They support the top ridges like a tent roof

Loops

• Loops– have ridges that start on one side– Curve and return to the original side– There may be as few as one looping ridge or more

than twenty• Ulnar loop

– Ridges start on the pinkie side (ulnar pinkie = UP)• Radial loop

– Ridges start on the thumb side

Whorls

• Plain whorl – a simple bulls eye pattern

• Central pocket whorl– has a small bulls eye pattern within a loop

• Double loop whorl – two intertwined loops whirl around each other

• Accidental or mixed whorl– has a mixture of loops, whorls, and arches in it

Plain Whorl Double Loop Central Pocket Accidental

Details in Prints

Aim Fingerprint 2b – what are minutiae and why do they make fingerprints individualizing?

Stupid Crime of the Day

• A man went into a drug store and announced his intentions to commit robbery.

• He pulled a Hefty Bag over his face to conceal his identity.

• He did not, however, cut eyeholes in the mask and was tackled by a brave customer.

• Fingerprint categories only group prints (identification)

• Minutiae in prints show the it’s uniqueness (individualization)

• Minutiae = the ridge details in a print

• Minutiae and AFIS- by finding and connecting minutiae- 12 to 15 minutiae required - a constellation pattern is created that a computer can search- AFIS uses algorithms to search for similar patterns

Three Ways Prints are Left at a Scene• Visible Prints

–An impression left behind when a finger is stuck in blood, oil, mud, ink, etc.

• Plastic Prints–a mold or cast of the fingerprint–can be left in soap, butter,

peanut butter, or any soft material –Case Study – “the Peanut Butter Bandit”

• Latent prints–an “invisible” fingerprint composed of sweat and oils

• Visualization –a method of making latent prints visible to the naked eye

Physical Methods of Visualization• Physical methods

– Use of powders and dusts to adhere to the residue in the print

• Powder dusting – powder comes in over 100 colors– only three actually used by police– black, gray, and white– advantage – cheap, readily available

• Magnetic dusting– use of metal laced powders to make prints visible– advantage – avoids touching of print

Illumination Methods of Visualization• Oblique lighting

–a light source is angled at a latent print

–photos taken or print is lifted later

–various colors of light can be used, including UV light

• Laser light –done the same way as oblique

lighting–Various wavelengths of laser

light can be used to find untreated latent prints

Chemical Methods of Visualization• Fuming

– reactive gases placed inside enclosed container with object to be visualized

– often used for gun triggers

• Cyanoacrylate (aka “Crazy glue”)– vaporizes (l g) with heat and deposits on oils in print

to form white residue

• Iodine – solid that sublimes (sg)

and deposits on oils (gs)– can be “fixed” with starch

(remember the test for starch in Bio?)

Chemical Methods of Visualization• Sprays and solutions

– a chemical sprayed directly onto print or item dipped in solution

• Ninhydrin– Reacts with amino acids in sweat– Most often used in document analysis– sprayed or dipped in solution

• Silver nitrate– sprayed on object and

reacts with salts in sweat– Can be used to find prints on

deceased bodies

Personal Individualization

Aim Fingerprint 3c – What are other ways to individualize a person’s identity?

An Oregon man went to jail after reportedly falling asleep on the kitchen floor of the home he was robbing in the wee hours of the morning. Police charged the man with theft, trespassing, and taking the term "cat burglar" much too literally. (Had to have a “cat nap”)

Personal Identification of PeopleForensic Odontology• Individualization based on dental evidence• Often requires the use of

known dental records for comparison

• Forensic dentist looks for individualizing characteristics– cavities and fillings– abnormalities (missing

teeth, extra teeth)– (Mis)Alignment of teeth

Personal Identification of PeopleForensic Odontology and Cases

• Can involve victim’s teeth when remains found • Or suspect evidence; e.g. Ted Bundy bite marks• Can be used in cases where only skeletal remains

are available for ID• Also used in accident and

other cases requiring ID

• Examples– TWA Flight 800 – World Trade Center victims

Personal Identification of People Body Marks

Body markings•distinguishing marks on the body•Either natural or manmade

– birthmarks– scars (from surgeries, injuries)– tattoos – often used to identify

gang members and convicts– piercings

NEVER go to a tattoo artist who got a 65 in

English

Personal Identification of PeoplePortrait Parle• “word picture”• simple description of what the victim (or suspect)

looks like• includes height, weight, possible age, eye/skin/hair

color, etc• Example: Suspect is:

– 6’4” and 285 pounds– Brown hair with streaks of grey– No facial hair– Strange eyes – close set…– Strange mark on face

Personal Identification of People

DNA Fingerprinting• the use of genetic material to individualize a

person or persons• Not 100% individualizing • 1 in 1 billion people have the same DNADNA• The genetic material found in nucleated cells• All cells except red blood cells• Sex cells – only half the genetic material

Personal Identification of PeopleDNA Macrostructure•23 pairs of chromosomes •make up the required 46 for human function•Chromosome structure

– Composed of long strands tightly wound

– DNA forms a structure called a double helix

– A spiral staircase shape

Personal Identification of PeopleDNA Micro Structure• DNA – composed of: • Nucleotide base pairs

– Adenine bonds with Thymine

– Guanine bonds with Cytosine

• Phosphate and sugar (ribose) backbone

• 1 billion base pairs form the 46 chromosomes of humans

Personal Identification of PeopleDNA Micro Structure• Only 1% actually codes

for anything• Every three base pairs in

a strand code for 1 amino acid

• Amino acids combine to form:– Proteins – provide

structure to body, ex: muscles

– Enzymes – catalysts that aid in biological reactions

Personal Identification of PeopleDNA Fingerprinting Process• Part 1 - PCR – Polymerase Chain Reaction

– The replication of the sample of DNA being studied

– Obtains many copies of the DNA in question

– How much DNA do we need for this process?

Personal Identification of PeopleDNA Fingerprinting Process•Part 2 – Cutting of DNA into RFLPs

– Restriction Fragment Length Polymorphisms– Pieces of DNA cut up by

enzymes– Separated in a special

process called gel electrophoresis – Pieces are separated according

to size– Then stained to become

visible

Other forms of Identification

Aim Fingerprint 4d – What are biometrics and do I actually use them in my daily life?

Personal Identification of PeopleVoiceprints• a measure of the pitch and frequency of one’s

voice• most often used in wire taps• Must be 70-90% viable to use in court

Personal Identification of People

Retinal scans• Photosensitive portion

of the eye• Have specific patterns that are individualizing• typically remains unchanged from birth until

death• Diabetes, glaucoma, degenerative disorders may

alter retinal pattern• But error rate is low (1 in a million)

Personal Identification of People • A device for scanning retina runs

around $3,000• Much less expensive to use than DNA

fingerprinting

• the retina appears to be the most precise and reliable biometric factor– Presently used by the US military– Animal health and tracking– Could be the future of airline travel!

Personal Identification of PeopleBiometrics • identification of people based on biological traits

– Very deep implications– Proving your identity is becoming an integral

part of your daily lives• Includes all of the previous identification factors:

– fingerprinting– palm prints– retinal scans– voiceprints– facial features

A Day in Your Life with Biometrics: Which of these are real and which are still in the works?

• You wake up, and check your email – and the computer requires a thumbprint to activate it…– True or False?

• You pull out your flash drive to check on the report you wrote last night and you use your thumbprint to open the drive…– True or False?SONY VAIO

A Day in Your Life with Biometrics: Which of these are real and which are still in the works?

• You head off to the garage

• A device on your car lets you unlock it…– True or False?

• Another device lets you start it up…– True or False?

A Day in Your Life with Biometrics: Which of these are real and which are still in the works?

• You decide to take the bus instead today. You get on the bus, and a facial recognition program charges your credit card automatically for the trip…– True or False?

• you go to a restaurant, and you use another thumbprint on a biometric scanner to pay– True or False?

A Day in Your Life with Biometrics: Which of these are real and which are still in the works?

• You decide to call a friend before you go into work; you speak into your phone and say “Call Fred”…– True or False?

• You get to work, and a fingerprint scanner allows you to enter the building…– True or False?

A Day in Your Life with Biometrics: Which of these are real and which are still in the works?

• You get to work, and a voice recognition panel allows you to enter the building…– True or False?

• You start work at your new job, Brothers/Brothers Blinker Foods in the customer service department, and have to send a letter to a dissatisfied customer… which do you do:– Type a form letter to the customer and beg forgiveness– Call direct and grovel– Travel to their home to apologize in person– None of the above