Presentation on theme: "Lin Wozniewski email@example.com Forensics Lin Wozniewski firstname.lastname@example.org."— Presentation transcript:
1 Lin Wozniewski email@example.com ForensicsLin Wozniewski
2 DisclaimerThis presentation was prepared using draft rules. There may be some changes in the final copy of the rules. The rules which will be in your Coaches Manual and Student Manuals will be the official rules
3 Safety Students must wear: Closed shoes Slacks or skirts that come to the anklesLab coat or lab apronIndirect vent or unvented chemical splash proof goggles. No impact glasses or visorgogs are permittedLong-Sleeved Shirt (if wearing a lab apron)Gloves are encouraged
4 Students can bring Spot plate or something to do reactions in Micrspatula or something to get powders outForceps/ Metal TongspH paperHand lens
5 Students Can Bring Test Tubes Test Tube rack Test Tube holder Eye droppersFunnelFilter PaperBattery Conductivity meterFlame loop/cobalt blue glassRulerCalculator
6 Students Can Bring Stirring rods or something to stir with Slide & cover slipPencilPaper towelsA test tube brush1 sheet of paper on which anything is acceptable.A writing instrumentNothing else is allowed
7 Supervisors will provide UnknownsIodine Solution2 M HClBenedicts Solution2 M NaOHDifferential Density materialsChromatography MaterialsWash bottle with Distilled or ROI waterCandle and matches
8 Supervisors will Provide Bunsen Burner or other heat source of similar BTUHot water bathWaste Container(Microscope?)(Other reagents?)
9 Crime Scene Physical Evidence How to prepare students Resources Main FocusChemical AnalysisPolymersChromatographyCrime Scene Physical EvidenceHow to prepare studentsResources
10 How To Prepare Students Have students develop a dichotomous key for identifying chemicalsPractice identifying chemicals in as short a time as possible.Practice identifying plasticsPractice identifying hairs (only human, dog, cat, bat, & horse possible)Practice identifying fibers
11 How to Prepare Students Practice doing pen chromatograms/doing RfPractice doing juice chromatograms/doing RfPractice doing TLC/doing RfPractice identifying masses from mass specsPractice identifying fingerprints-primary and secondary structure
12 How to Prepare Students Practice matching DNA chromatograms/electropherogramsPractice matching shoes & tires to their tracksPractice blood typingDo a liquid spatter activityPractice using a waste containerDo a glass refractive index activity
13 Resources Plans for classroom use To prepare For Event Supervisors The National SO WebsiteTo prepare For Event SupervisorsFor Lesson students for testSource for mass specs /~lwoz/socrime/index.htm
16 Time to PlayI have a crime for you to solve if you want to get your hands wet so that you will know what you are doing with your studentsI am prepared to show you how to do any of the tests with either knowns or unknowns except the flame testsWhat do you want to do? Some can work & I will help while others may have specific requests of me
17 Crime Let’s solve the crime Step one – read over crime Best to divide and conquerOne partner starts on chromatographyOne partner starts on Qualitative AnalysisPartner finishes chromatography & starts polymersShould finish in about 30 minutes and have remaining time to analyze.
18 Chromatography Used to separate mixtures into components Uses stationary (paper or TLC sheet) and mobile (water or solvent) phasesDepends on affinity of molecules for the 2 phases for how fast molecule movesStrip or SheetDraw a line ~ 2 cm from bottom in pencilSpot on line. Use toothpick for liquids.Use pencil to label at top above spot.Put bottom only of paper in waterPut TLC in chamber w/air saturated with solvent
19 Chromatography Continued Wait until water moves up ~ 3/4ths of paperDraw line with pencil where water or solvent has moved toMake middle of each distinct separated moleculeMeasure from bottom line to each molecule markMeasure from bottom to solvent lineDivide distance molecule moved by distance solvent moved to find RfExamine TLC under UV light
20 Qualitative AnalysisStart with a well thought out, practiced dichotomous schemeWhat is our powder?Green Flame?YesBoric AcidNoRed Flame?Lithium ChloridePurple Flame?Potassium ChlorideBurns?Turns Blue/Black w/Iodine?CornstarchTurns Benedicts Yellow/red?GlucoseSucroseBubbles-Boils?Magnesium SulfatePolymerizes?Ammonium ChlorideRed/Orange sparkles?Calcium NitrateDoes Not Burn ?Glows bright white?Calcium CarbonateCalcium SulfateYellow Flame?Fizzes w/HCl?CheckpH8?Sodium Bicarbonate10Sodium CarbonatesCheck pH6?Sodium ChlorideSodium Acetate
21 Plastics A good dichotomous scheme needed here too. So what is our plastic?
22 Fiber AnalysisNeed to know the difference between Wool, Silk, Cotton, Linen, and Nylon, Spandex, and Polyester fibersEasiest to identify with burn testAnimal shrivel in heatWool shorter fibers than woolVegetable burnCotton shorter fibers than LInenSynthetic melt.Spandex stretchesSo what is our fiber?
23 Hair Analysis Only allowed to use Human, Dog, and Cat, Horse, and bat Best identified by looking at microscope.Horse very thick and round.Human hair thick, no distinct cuticleCan be flat or roundCat hair thinnest, distinct palm tree or braided cuticle.Dog hair in between thickness and in between cuticle.Bat hair looks like chocolate strawberries on a stickWhat type of hair was found at scene?
24 Soil Analysis Sand, Silt, Clay, and Loam Students allowed to touch soil to analyzeSand-large grains, does not ball in handClay-very small grains, forms ribbons in fingersSilt-medium grains, forms ball, but falls apartLoam-lots of organic material, blackWhat type of soil was found at scene?
25 Fingerprints Need to know Whorl, Loop, and Arch Arch- hill-no deltasTented Arch-higherLoop – radial & ulnar-around the lake -1 deltaDouble LoopPlain Whorl-target-2 deltasCentral Pocket Whorl & AccidentalWhat type of fingerprint?
26 FingerprintingEmphasis is on understanding the chemistry of how the fingerprinting worksBody gives off oils and salts that the chemicals adhere to.Some methods of fingerprinting are better fro some applications than others.If fingerprinting small, hard, solid object any method will work.If large object, can not put in a developing chamberSome methods of fingerprinting destroy object
27 DNANeed to understand chemistry behind method of reproducing enough DNA for analysis (PCR).Nobel prize won in 1985Easy to make electropherogramsMake rectangle with drawing programUse spray tool to spray in different width, density lines at various distances.Students should understand basic structure of DNA
28 Tracks More pretty picture matching, but inverses. Bike tracks easy to get at a bike rodeoHave cookie sheet filled with sand,Take a picture of tire, run through sand, and take a picture of track.For footprints photo bottom of shoeStomp in cookie sheet of flourStomp onb lack construction paperPhotograph paper
29 Index of RefractionLight travels at different speeds through different materials.Light travels slower through denser mediaLight bends when it goes from one medium to another.The index of refraction is the ratio of the sine of the angle the light makes coming in compared to the sine of the angle in the new mediaObjects disappear when put in a liquid with the same index of refraction
30 Blood Serology Student should recognize human blood cells (round, no nuclei 6-8/ microns),avian blood cells (elliptical, single nucleus, 6-12 microns)mammalian blood cells (no nuclei, microns, can be elliptical or round)reptile/amphibian blood cells (multiple nuclei).What animal’s blood was found at the scene?
31 Blood Typing Can not use real blood Blood typing works on which sugars on cell walls, A, B & OAnti A clumps A cells together, etc.Fake blood can be made of several recipesThe one I use is a precipitation reactionIt requires the students stir to precipitate-seems realisticWhat type of blood was found at the scene?
32 Spatters NOT MEASURING ANGLES Should know if strait drop or angle Should know if spatter is high or lowI start with red finger paint, then mix in blue and green until correct shadeThen I dilute with water slowly until proper consistency.Students should put in eye dropper or use paint brush and drop straight 1 cm, 10 cm. 20 cm, etc.
33 Entomology Depends on predictable life cycle of flies. Depends on temperature body experiences after death.It is assumed that flies will lay eggs immediately after deathEggs hatch in ~1.5 days as maggots(shows 3 instars)Maggots pupate in ~ 5 daysFlies immerge in~ 15 days
34 Seeds and PollenMostly useful if found away from an area naturally foundCan be useful if embedded in hair or furSmall seeds are generally windblown, but can get caught in clothing and hairSeed placement can also be very useful in placing time of a crime.Pollen very useful because pollen is very species and subspecies specific.Pollen needs to be compared under a microscope
35 Bullets This is mostly pretty picture matching The idea is to match the scratch pattern on two bullets to determine if they have been fired from the same gun.The scratches are a result of the machining done when the gun was made.In real crimes this is done with a special microscope that allows the technician to see both bullets at the same time.
36 The Crime Now we use all of the results to solve the crime. Logic is used.It is a preponderance of evidence that is used to solve the crimeThe correct answer may be one of the suspects, more than one of the suspects, all of the suspects, or none of the suspects.
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