Impressions CHS Forensics Types of impressions Tool Marks

Impressions CHS Forensics

Types of impressions Tool Marks Shoe Prints Tire Tracks Bite Marks Mr. Mc. Niff

Tool Marks A tool mark is any impression, cut, gouge, or abrasion caused by a tool coming into contact with another object. Most often tool marks are encountered at a burglary scene that involves forcible entry. Mr. Mc. Niff

Tool Marks cont. Typically tool mark impressions are left behind on the frame of a door or window. Careful examination of the marks can yield class characteristics, size and shape of the tool. Mr. Mc. Niff

Tool Marks cont. Small random striations during manufacturing of the edge of a pry bar, chisel, screwdriver, or knife will have microscopic irregularities, ridges and valleys. These irregularities are enhanced by usage, where the tool, through use, can become damaged giving individual characteristics. Mr. Mc. Niff

Tool Marks cont. When the tool is scraped against a softer material these minute marks are left behind. These minute marks are matched to the suspected tool using a comparision microscope. Mr. Mc. Niff

Tool Marks cont. When the evidentiary materials cannot be brought back to the lab or is to big to be placed under the microscope, casts are made of the tool marks using liquid silicone. Mr. Mc. Niff

Tool Marks cont. Under no circumstances is the suspected tool and the evidentiary material to come into contact. This could compromise the evidence and will cast doubt on the integrity of the evidence Mr. Mc. Niff

Types of impressions Tool Marks Shoe Prints Tire Tracks Bite Marks Mr. Mc. Niff

Shoe Print Shoe prints can be left on multiple surfaces. The first step with handling shoe print evidence is to photograph the print at multiple angles. Mr. Mc. Niff

Shoe Print cont. 2 -D: This type of impression is a flat deposit of dust and dirt. Some impressions can be dusted with fingerprint powder to be photographed or lifted with tape or an electrostatic dust lifting process called “Pathfinder”. Mr. Mc. Niff

Mr. Mc. Niff

Shoe Print cont. 3 -D: prints can be made from shoe prints left in soft earth. This type of impression is photographed first then casted Casting involves the using dental stone (gypsum) or a similar substance to preserve the dimensional characteristics of the print. Mr. Mc. Niff

Dust and dirt hardener firms up loose soil. Mr. Mc. Niff

Mr. Mc. Niff

Mr. Mc. Niff

Shoe Print cont. Investigators can analyze a shoe print to determine its class, or the type and brand of shoe. They will also look for individual characteristics, such as wear patterns and specific damages or defects. Mr. Mc. Niff

Mr. Mc. Niff

Shoe Print cont. Depending on the quality of the impression, investigators may be able to determine a person’s speed (walking vs. running) as well as estimate the size of a person based on the impression’s depth. Mr. Mc. Niff

Footwear impressions are found at virtually every crime scene Footwear impression evidence often provides an important link between the suspect and the crime scene. Impressions left behind at the crime scene give the direction the suspect traveled while committing the crime. This information may place the suspect at the crime scene or eliminate the suspect as having been there. Mr. Mc. Niff

Mr. Mc. Niff

Mr. Mc. Niff

Types of impressions Tool Marks Shoe Prints Tire Tracks Bite Marks Mr. Mc. Niff

Tire Tracks Tire tracks are usually found in road accident scenes or in the access and escape routes of other crime scenes. Tracks help the type of investigators identify vehicle that left them. Mr. Mc. Niff

Tire Tracks Cont. Investigators may make ink prints of a tire or plaster casts of a track. They will also take photographs that can later be used to prove a match. Texas’s unsolved Phantom killer Mr. Mc. Niff

Tire Tracks Cont. Features to analyze: Tread pattern Width & depth of the tread pattern Unique characteristics due to the wear pattern or defects Mr. Mc. Niff

Types of impressions Tool Marks Shoe Prints Tire Tracks Bite Marks Mr. Mc. Niff

Forensic anthropologist Bill Bass, left, and his co -author, Jon Jefferson, examine a decaying corpse on the Body Farm. Bite Marks Human bite marks on skin, Styrofoam cups, gum or food can be helpful in murder and rape cases Dental records including x-rays can also provide useful information, especially when attempting to identify a victim. Mr. Mc. Niff

Features to analyze: Type of bite mark (human or animal) Characteristics of the teeth (position, evidence of dental work, wear patterns, etc. ) Color of area to estimate how long ago the bite occurred (old or recent bite) Mr. Mc. Niff

Mr. Mc. Niff

Mr. Mc. Niff

Mr. Mc. Niff

Types of impressions Tool Marks Shoe Prints Tire Tracks Bite Marks Mr. Mc. Niff

Pictures Slide background http: //static. howstuffworks. com/gif/impression-evidence-1. jpg http: //www. maine. gov/dps/msp/criminal_investigation/crimelab/footwear. htm http: //www. istockphoto. com/file_thumbview_approve/2086687/2/istockphoto_2086687 -nine-tire-tracks. jpg http: //www. forensicsciencesfoundation. org/career_paths/images/Fig 7 Comparison. jpg http: //www. physics. unlv. edu/~jeffery/astro/moon/onmoon/nasa_footprint_apollo 11_002. jpg http: //www. webweaver. nu/clipart/img/people/mouths/teeth-chattering. gif Slide 2 http: //1. bp. blogspot. com/_z. BH 03 E 9 jg 5 w/Sghp. QZh. Rg. YI/AAAABCE/n. YEAockrl. Bs/s 400/tool+mark+2. jpg Slide 3 http: //www. dps. state. ia. us/DCI/lab/firearms/toolmark_ID. shtml Slide 4 http: //www. focossforensics. com/html/toolmarks. html http: //www. state. nj. us/njsp/divorg/invest/ofs/images/tools 1. jpg Slide 5 http: //www. fei. com/uploaded. Images/Image_Gallery/Tool_Marks_on. Cut_Wire_lg_240. jpg http: //www. leedsforensics. com/home. asp http: //www. maine. gov/dps/msp/criminal_investigation/crimelab/toolmarks. htm Slide 6 Slide 8 http: //www. wagnerandson. com/images/bm_heel. jpg Slide 9 http: //science. marshall. edu/murraye/images/_42571001_shoe_print_fss%20 forensic%20 science%20 s ervice. jpg http: //kulkul. xahoihoctap. net/collection/scientific-terms/electronmicroscopy. html? view=mediawiki&article=Forensic_footwear_evidence Slide 10 http: //www. bvda. com/EN/ENimage/dlk_lift. gif Slide 11 http: //intercsi. com/new/components/com_virtuemart/shop_image/product/74 acee 42 ec 70 a 901453 aa 87898 c 3 c d 22. jpg Mr. Mc. Niff

Pictures Slide 11 http: //www. evidentcrimescene. com/cata/casting 2. jpg Slide 12 http: //www. leelofland. com/wordpress/? p=143 Slide 13 & 14 http: //www. evidentcrimescene. com/cata/cast/dscasting. html Slide 15 http: //www. okjordans. com/images/jordan-1 -14. jpg http: //www. fbi. gov/hq/lab/fsc/current/review/2009_07_review 02. htm Slide 16 http: //www. fbi. gov/hq/lab/fsc/current/review/2009_07_review 02. htm Slide 18 http: //www. state. nj. us/njsp/divorg/invest/ofs/images/footwear 3. jpg Slide 20 http: //www. truckautoaccidentlawyer. com/car-wreck-cropped. jpg http: //thehealingtouch. files. wordpress. com/2008/05/4295 -gta-iv-multiplayer-hit-hard 1. jpg http: //www 1. agric. gov. ab. ca/$department/deptdocs. nsf/ba 3468 a 2 a 8681 f 69872569 d 60073 fde 1/e 7 a 62 f 10 b 2115 e 9 f 87 256 c 150077085 f/$FILE/fsets 5 bl. gif Slide 21 http: //www. texasranger. org/history/images/Tire. Track. gif Slide 23 http: //www. ncforensicodontology. org/media/photo_apple. jpg http: //www. theage. com. au/articles/2004/01/16/1073878020713. html Slide 24 http: //www. geradts. com/anil/ij/vol_005_no_002/reviews/tb/book 008/01_24. jpg http: //tvtropes. org/pmwiki/pub/images/Shark. Attack. jpg Slide 25 http: //www. fbi. gov/hq/lab/fsc/backissu/july 2001/bowers. htm Slide 26 http: //www. nlm. nih. gov/visibleproofs/media/detailed/vi_c_301. jpg Mr. Mc. Niff

References http: //www. fbi. gov/hq/lab/fsc/current/review/2009_07_review 02. htm Saferstein, Richard. Criminalistics an introduction to forensic science. Upper Saddle River, N. J: . Prentice Hall, 2004. Print. Music http: //www. rosswalker. co. uk/movie_sounds/jaws. htm Mr. Mc. Niff