11 What happens??An impression is made…. This would be your tire tracks, foot prints, etcThen it is filled with a plaster that is mixed upThis is allowed to dry and it pulled out of the impressionTHEN YOU END UP WITH…..
19 RECOVERY Tire impressions must be: Photographed from all angles with and without measurement tool (ruler)Cast – a 3 foot impression requires pounds of dental stoneMeasured – width, length and depthDirection of travel notedImpressions made if possible, andPictures of the source (tire) must be included for comparison
20 COMPARISONSTire tread examinations compare the tire impressions recovered from scene with tires taken from a known vehicleTwo categories of tires:Suspect - Vehicle of suspectElimination - Vehicles of police, ambulance, etcAll tires should be seized from suspect vehicle for comparison
21 COMPARISONSForensic examination begins with visual comparison and elimination of tires which do not match impressionForensic examination continues with full circumference test impressionsImpressions are superimposed on known impression over cast or original tire
22 So what did we learn already?? Tire tracks would be considered what type of evidence???CLASS!!!!
23 Tire tracks can be individualized how???? Wear marksNails in tiresPatchingGravelSkidding caused by sudden stops
25 Your group will need to document the tread patterns for each vehicle. Tire Track LabStep 1: Get a large piece of white paper from your teacher, an ink pad, paper towels, and a ruler. You will also need a pen or pencil.Step 2: Gently roll a car over the ink pad several times to cover all the sides of the tires.Step 3: Gently roll the car on the white paper for a length of 5-6” and label the tracks with the car’s letter.Caution: You will want to apply enough pressure to get a good impression, but not too hard that you cause damage to the vehicle, its tires, or the ink pad.Step 4: Roll the car on a piece of paper towel to remove excess ink and then pass it along to another group.Step 5: Analyze the tire tracks to identify unique characteristics, such as blank spots, evidence of tire wear, width of the track, etc. Use a highlighter to mark each characteristic you find.
26 Ready? Set? GO! Tire Track Challenge Work with your investigative team to identify each set of tracks shown on your worksheet.Compare the tracks you made earlier and match them to the suspect tracks on the worksheet. Once you have identified all the cars, have your answers checked by your teacher.Ready?Set?GO!
27 WARMUPWhy are tire tracks so hard to trace to a source? What would make them easier to link to a suspect’s vehicle?
33 Things Prosecution Looks for When Examining Footprints The walk or gait of the person who left the footprints,Sole or heel indentsCuts or the tread of a shoe, andOther signs of wear associated with a shoe.
34 Investigators can determine a person’s size and the speed (Running or walking) they were going
35 GaitA manner of walking or moving on foot. It can be as individualized as your personality.
36 Three things are needed to actually use footprints to convict someone…. A photography, plater mold, or print of the original and un-tainted footprint,The actual shoe or mold of a foot that belongs to the defendant and the prosecution believes matches the one at the crime sceneAn expert witness that can testify to the connection between the two beyond a reasonable doubt.
40 DIRECTIONS Meaure length of shoe you’re wearing by standing on ruler Have someone measure your heightCollect similar data from your classmatesPlot height (y axis) against shoe length (x axis). One set for males, one set for females
41 Questions to ConsiderIs there a correlation between shoe length and height?How could investigators utilize this information?
42 WARMUPWhat steps would a detective take to determine who a suspect is based on footprints?
46 How can tools be used in a crime? Stabbing or hitting another individualBreak into things
47 Features to Analyze Dimensions of the impression Ridges or striation patternsDefects, such as nicks and chipsPaint chips or metal shards left on a tool
48 Places and Surfaces Where Tools Might Be Used wire,chainsdoor and windowframessections of sheet metalsafety-deposit boxes,human bone or cartilagepadlocks, doorknobsbolts and locksand a variety of other materials
49 Main Tools Used At a Crime Scene bolt cuttersscrewdrivers and chiselsscissorsknives and box cutterspliers and wrenchescrowbars tire ironssaws, knivesRead more at Suite101: Toolmarks at a Crime Scene: Forensic Criminal Investigations can Link Toolmarks to Tools | Suite101.com
50 Tools Can Be Classified Two Ways ImpressionScratches
51 Class and Individualized Characteristics Class- Size and shape of tool.Individualized- As tool is used more it becomes worn and damaged
53 Goal: Your group will need to examine and document the tool marks made by each of the tools. Tool Marks Lab At each station, you will need to: 1 – To prepare for the lab, roll the modeling clay into a flat circle that fits inside the plastic plate. Make several impressions of each tool in your slab of modeling clay.2 – Use the ruler to record the measurements for each tool and its impression surfaces.3 – Document any unique characteristics you notice on each tool or its impression. Write your observations on your worksheet.4 – After you have documents both of the tools at that station, roll the clay into a ball to prepare for the next group and wait until it's time to rotate to the next station.Features to analyze:Dimensions of the impressionRidges or striation patternsDefects, such as nicks and chipsPaint chips or metal shards left on a tool Image:
54 On your mark? Get set? Go! Tool Mark Challenge Work with your investigative team to identify the crime scene tools.Compare the tool marks you made earlier and match them to the crime scene tools. Once you have identified all the tools, have your answers checked by your teacher. Keep trying until you have them all correct!On your mark?Get set?Go!
55 How can a tool mark be individualized? WARMUPHow can a tool mark be individualized?
64 Bite Marks Were One Main Piece of Evidence Used to Convict Ted Bundy
65 Bite Mark Identification Presentation developed by T. Trimpe 2010
66 Part 1: Make an Impression 1 – Fold the Styrofoam plate in half.2 – Label one side MAXILLA and the other MANDIBLE.3 – Gently bite down on the plate to leave your bite mark impression.4 – Place a sheet of the plastic film over the impression and use a permanent marker to recreate the pattern to match that of your bite mark.5 – Use a ruler to make the measurements shown and record in the table below along with any notes regarding unique characteristics you observe in the teeth.MaxillaMandibleDepthMaxillaWidthMandible
67 Part 2: Tasty Testing1 – Use the various pieces of candy to make bite mark impressions.2 – Record your observations for each one as well as provide a rating of the impression quality using poor, fair, or good.Type of CandyQualityObservations
68 What did you learn from the bite mark activity yesterday? WARMUPWhat did you learn from the bite mark activity yesterday?