LAB FINGERPRINTS



FINGERPRINT LIFTING LAB INSTRUCTIONSPART 1 - Balloon PrintsMaterials: White balloons Fingerprint ink pad MarkerProcedure:Partially inflate a balloon. Do not tie it off!Open fingerprinting pad and gently roll one fingertip.Apply finger to balloon surface near the center (where the balloon will expand the most), being careful not to smudge or twist while lifting the finger from the balloon surface.Each group member should place one print on the balloon.Inflate the balloon as much as possible without it breaking and mark each print with your name, hand (right or left), and fingerprint pattern (ulnar loop, radial loop, plain arch, tented arch, central pocket whorl, plain whorl, accidental whorl).Circle and name 4 different minutiae on each print. Record all data below.Group Balloon DataName/Hand & Finger UsedFingerprint Pattern Observed (1 print)Minutiae Observed (4 for each print)PART 2 - Graphite Prints (Plastic Prints)Materials: Pencil Paper Transparent Tape Index cards Procedure:Hold the pencil at an angle on paper and fill a small area with graphite.Roll the tip of one finger (different from Part 1) over the shiny graphite, making one or two passes. Good technique demands including the entire fingertip, edge to edge and down to the area of the first joint. Keeping the paper at the edge of the table will make this easier.Have your partner pull 2 – 3 inches of tape, while only touching the ends and keeping the sticky side up.Roll your graphite-covered fingertip onto the tape.Carefully place the tape containing the fingerprint onto an index card. Label each print with the type (ulnar loop, radial loop, plain arch, tented arch, central pocket whorl, plain whorl, accidental whorl), hand (R or L), finger, and your name. Repeat for each person in the group using a different card.Tape your card in the space below. Read the handout and answer the questions below.Questions: 1. What are the three different types of prints found at a crime scene? a. _________________c. _________________b. _________________2. Explain each type of print above in the space below.a. __________________________________________________________________________________________________________________________________________________________________________b. __________________________________________________________________________________________________________________________________________________________________________c. __________________________________________________________________________________________________________________________________________________________________________3. Which type of print would you classify your graphite print as? __________________________________Why? _________________________________________________________________________________My Graphite Print CardPART 3 - Inked PrintsMaterials: Ink Pad White Paper Fingerprint Card Reference Paper (Good and Bad Prints)Procedure:On a sheet of scrap paper, practice rolling your lab partner’s prints. Remember the techniques demonstrated in the video. [Good technique demands including the entire fingertip, edge to edge and down to the area of the first joint. Keeping the paper at the edge of the table will make this easier!]When rolling onto the paper, make one smooth, even motion. Look at the reference paper showing good and bad prints.Have your teacher check your work. When you feel comfortable with your technique, roll a full set of prints on the fingerprint card. Only card per person.When the prints are dry, label each of your print patterns for all 10 fingers (ulnar loop, radial loop, plain arch, tented arch, central pocket whorl, plain whorl, accidental whorl) on the card below or above each print.Determine your primary category (loop, arch, or whorl), showing your work. Attach your labeled fingerprint card to the lab packet when you are done. PART 4 – Lifting Latent PrintsMaterials: Ceramic Tile Index cards Packing TapeBlack PowderWandProcedure: Lifting latent prints takes time and patience. We will use black powder since it works well on nonporous surfaces like glass and is less messy than other powders. Obtain a ceramic tile, if needed wash and dry it well. Hold it by the edges only.Rub a finger over the surface of your forehead or some place where you will pick up skin oils.Make some prints using this finger on the tile.Lightly brush a very small amount of powder over the print. Too much or too little powder can make it difficult to see the minutiae. [If you are not sure how to use the wand ask for help.]Take a piece of packing tape and roll the edges to help you control it. Do not touch the sticky side of the tape. Place the tape over the entire print and lightly rub your finger across the tape, forcing out all the air bubbles. Lift the piece of tape off the tile and place it on an index card. Label the card with your name. Each person in the group should lift a fingerprint. Tape the card containing your lifted print below.My Lifted Latent PrintPART 5 – Developing Latent Prints by Cyanoacrylate (Super glue) Fuming POISON, CAREFUL!Materials: Microscope slide (plastic preferred)Superglue Small jar Aluminum foil Hair blow dryer Procedure:Place a fingerprint, or several fingerprints, on a clean microscope slide. Use the finger which print you examined previously in Part 2 (the graphite fingerprint).If not there already, place a small piece of aluminum foil in the bottom of the small jar. Add a few drops of superglue onto the aluminum foil. [This will prevent the microscope slide from becoming glued to the bottom of the jar.]Place the microscope slide into the jar and close it.Allow this to stand for at least 5 minutes and up to 30 minutes. [See Figure 1] You should be able to see the fingerprint developing on the microscope slide. [Note: this procedure can be speeded up by warming the container slightly with the blow dryer.]Remove the slide with the developed fingerprint from the jar. Attach the slide below.Super Glue Fuming SlideFigure 1Questions:Examine the fingerprint. Determine the fingerprint pattern and then identify as much of the minutiae as possible. List below:Pattern:____________________________________________________________________Minutiae observed: ____________________________________________________________________________________________________________________________________Compare the developed fingerprint to the graphite fingerprint. Can you make a definite match? Explain.___________________________________________________________________________________________________________________________________________3. When is superglue fuming appropriate to use? ____________________________________________________________________________________________________________________ PART 6 – Ninhydrin Developing for Latent Prints POISON, CAREFUL!Materials: Fume hood/open window Gloves Paint brush Ninhydrin solution Index cardProcedure:Make several latent prints on a labeled (with your name) index card – one card per person.Careful--ninhydrin can react with the amino acids in your skin and turn it purple/blue as it will when it reacts with the amino acids in the print. Wear gloves and keep the solution away from open flames. While under the fume hood/near open window, dab the print with a small amount of ninhydrin. Do not use too much pressure.Leave the card at the side of your lab table to dry for 24 hours. Attach your labeled card Ninhydrin Developed PrintPART 7 – Developing Latent Prints with Iodine Crystals POISON, CAREFUL!Materials: Small strip of index card Iodine crystals in a closed jar Fume hood/Open window GlovesProcedure:Place several latent prints on a labeled (with your name on back) strip of index card - one card per person.While under the fume hood or near an open window and while wearing gloves, place the strip into a small jar containing iodine crystals. Do not breathe the vapors! Quickly close the lid and allow the print to develop for 5 – 10 minutes. Use forceps to remove the paper from the jar. Show the print to your teacher to be given credit. Have them sign below after viewing. NOTE: Iodine sublimes and will quickly leave the paper. (Starch spray can be used to help save the print.)Teacher Signature: ___________________________________________PART 8 – Developing Latent Prints with Silver Nitrate (AgNO3) POISON, CAREFUL!Materials: Fume hood/open window Silver nitrate solution Paint brush Index cardProcedure: Place several latent prints on a labeled (with your name) index card - one per person in your group.While under the fume hood or near an open window and while wearing gloves, dab the print with a small amount of silver nitrate solution. Silver nitrate (AgNO3) reacts with salt (NaCl) on the skin and will change your skin and the print a black or reddish-brown color.Allow the card to dry at the side of your lab table. Attach the card below.Silver Nitrate Developed Latent PrintQuestions:Which method (ninhydrin, iodine crystals, or silver nitrate) showed the fingerprints most clearly?______________________________________________________________________________________________________________________________________________________________Why is it necessary to use different fingerprinting methods at crime scenes?__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________PART 9 – Fingerprint ID Materials: Hand lens Fingerprints ID handoutProcedure:Identify the pattern in each print and record the category and sub-category of each print below.Print LetterCategory/Sub-categorya. With the information given, why was it impossible to distinguish ulnar and radial loops?______________________________________________________________________________________________________________________________________________________________b. How are loops, arches, and whorls distinguished?______________________________________________________________________________________________________________________________________________________________PART 10 - Identify a Suspect with Fingerprints -“Sticky Fingers” ActivityMaterials: Hand lens Crime scene and suspect fingerprints handout Three weeks ago a local bakery was robbed at gunpoint. The thief wore a mask, so even when the police found a suspect the bakery owner couldn’t make a positive ID. However, as the CSI processing the scene, you collected several fingerprints from various parts of the bakery. The police have identified a suspect, but he says he’s never been to that bakery. It’s your job to see if the suspect’s fingerprints match any of those recovered at the scene of the crime.Questions: 1. Can you identify any ridge characteristics on the suspect’s prints? On the prints from the crime scene?On your handout, circle and label any ridge characteristics you find.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Do any of the crime scene fingerprints match the suspect’s fingerprints? Label any matching crimescene fingerprints with the hand and finger they come from on your handout.__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________3. Do any of the crime scene prints NOT match the suspect’s prints? Who do you think could have contributed these prints? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________4. Do you think the suspect committed this crime? Why or why not? ___________________________________________________________________________________________________________________________________________________________________________________________________________PART 11 – Fingerprint ChallengeMaterials Fingerprint Challenge worksheet (one per person)Complete the challenge worksheet (one per person) by matching the prints outside of the question mark to the ones inside of the question mark. Record your answers below:A = ____F = ____K = ____B = ____G = ____L = ____C = ____H = ____D = ____I = ____E = ____J = ____ ................
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