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Warm upWarm up• Which type of fingerprint are the

following?

electronic devices will be confiscated

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Warm up answersWarm up answers• All loops

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Turn in fingerprint Turn in fingerprint homeworkhomework

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Today’s activitiesToday’s activities• Developing fingerprints on porous

surfaces (paper, cloth, etc.)

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• Ninhydrin + Amino Acid = • Ruhemann’s purple + carbon dioxide

+ aldehyde + water

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Lab set upLab set up• Exhibit B – each student place a good

print from any finger on filter paper. Label with student name

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Data collectionData collection• Exhibit B – you will develop the print

using ninhydrin.

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Lab set upLab set up• Exhibit C – each student place a good

print from any finger on index card. Label with student name

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Data collectionData collection• Exhibit C – you will develop the print

using iodine.

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Procedure for data Procedure for data collectioncollection

• Exhibit B - Place the print on a paper towel. Spray with ninhydrin (the paper should get damp, but not wet). Allow paper to absorb the solution before picking it up to fan to speed up drying. Once dry, hold the paper a few inches over the hot plate for 2-3 minutes until the print appears.

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Procedure for data Procedure for data collectioncollection

• Exhibit C – Put the index card in the iodine chamber. Remove it when the print develops

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Fingerprint identificationFingerprint identification• You must now identify each of your

pieces of evidence.• Begin by determining which

classification each print is, this will narrow down your search to only those fingerprints which match that category.

• To confirm the identity, you must diagram 12 points of commonality.

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identification (cont)identification (cont)• If available, a photocopier or digital

imaging can be used to enlarge the print.

• Otherwise, use a dissecting microscope or magnifying glass

• Using the “types of minutiae” sheet, identify the 12 points of commonality

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You must turn in You must turn in (case # 4 fingerprints)(case # 4 fingerprints)

• For today:• Your partner’s complete M. O. sheet (IAR

13b)• At least 1 print from soft surface with

analysis/points of commonality (IAR 13a)• For last class:• Your partner’s complete M. O. sheet (IAR

13b)• At least 1 print from hard surface with

analysis/points of commonality (IAR 13a)

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Cool downCool down• List the 3 types of fingerprints and

the subtypes of each. Which type do you have on each of your fingers?