Evidence Collection & Chain of Custody PDF

Evidence Collection & Chain of Custody  Introduction to Physical Evidence Physical Evidence Evidence that can be used in a court based on forensic science Physical Evidence will only be admitted at trial if the legal rules have been followed from the crime scene to the cour...

Evidence Collection & Chain of Custody  Introduction to Physical Evidence Physical Evidence Evidence that can be used in a court based on forensic science Physical Evidence will only be admitted at trial if the legal rules have been followed from the crime scene to the courtroom The steps in Evidence Collection are: 1) Secure the crime scene 2) Locate the evidence 3) Document the evidence Videos, Photos and Sketches 4) Collect & Package the Evidence  Important Considerations There are important guidelines to consider when collecting evidence: Always wear personal protective gear Gloves, Disposable shoe covers, face masks Change the personal protective gear to avoid cross contamination Good rule of thumb when changing rooms Evidence that will be tested should be packaged separately Avoids cross-contamination Packages should be clearly labeled with the item number Plus case number, initials of person sealing it, date and location All packages should be sealed with tape and initialed  Collecting Hazardous Materials Hazardous materials Substances which are a risk to health, safety, property, or the environment Occasionally, crime scene technicians will run into evidence that is hazardous to store and transport Shipping of hazardous forensic evidence must comply with the US Department of Transportation (DOT) and International Air Transport Association regulations When mailing evidence that may be at risk of bloodborne pathogens, the container needs to be marked with a biohazard warning label All information relating to hazardous properties, disposal techniques, and emergency preparedness are found on a Safety Data Sheet  Collecting Human Remains There are occasions when human remains will have to be shipped for specialized examination In Texas, a body cannot be moved until the Justice of the Peace signs off on a death certificate Guidelines: Collect bones in paper bags Use tin foil around very fragile bones Fresh/wet tissue needs to be sealed in plastic Add ice packs with tissue samples Label the package with the Biohazard labels  Collecting Entomological Evidence The use of insect life cycles and succession can provide evidence on how long someone has been dead and what they died from Guidelines: Adult and Flying Insects Catch with an insect net Place in 70% isopropyl alcohol mixed 1:1 with water Crawling Insects Use forceps; place in above solution Maggots Record temperature of mass, body and air Collect largest maggots from multiple sites; place in solution  Collecting DNA Evidence DNA Evidence may be found in a variety of fluids at a crime scene and is the most valuable forensic evidence for trial Examples of evidence that may have DNA: Cigarette butts, chewing gum, envelopes, blood, urine, semen Guidelines: Pick up physical items with forceps For fluids (wet or dry), use lab grade Q-tips Add distilled water Lightly rub for 15 seconds Let air dry in appropriate container Refrigerate until mailing  Collection of Blood Samples (DWI) In Texas, only a qualified medical expert, with consent or a search warrant, can collect blood from a live person This is very commonly done with Driving While Intoxicated cases and the blood samples are analyzed by DPS to get a Blood-Alcohol Concentration Guidelines: Collect two 5mL tubes of blood Label each tube with case number Refrigerate the blood samples Package in Styrofoam Label it with the Biohazard label  Collecting Hair & Fiber Evidence Fiber examinations can determine the type of fiber and then can also be compared to known fibers for consistency Hair can be determined to be animal or human; analysis can reveal race, body area, decomposition, and any alteration Fiber Guidelines: Submit the entire garment if possible Submit in a druggist fold then an evidence bag Hair Guidelines: Package samples from different areas separately Submit in a druggist fold then an evidence bag Take at least 25 hairs from a person for sampling  Collecting Firearms & Bullets Ballistic experts can determine whether a bullet was fired from a specific firearm Safety is stressed as not to mail a loaded firearm Guidelines: Package bullets separately Follow US DOT guidelines for live ammunition Package cartridges separately All firearms must be unloaded Handle it minimally Ship all evidence separately  Collecting Paint & Toolmark Evidence Paint chips can provide the color, manufacturer, model and year of an automobile Tools and toolmark evidence can be linked through lab analysis Guidelines: Provide control paint chips from car/object Package in leakproof containers Pillboxes, screw top vials Do NOT use plastic bags, cotton or envelopes Submit the tool itself Do NOT place the tool against the evidence  Collection of Footprint & Tire Impressions Footprints and tire impressions are commonly found at crime scenes Soles and tire patterns can be matched to a national database to determine brand and manufacturer Photographs or casts may be submitted Guidelines: Submit original evidence if possible Air dry and package evidence separately Casts should be covered in bubble wrap and paper Footwear or tire impressions in snow should be sprayed with a color spray before photographing  Collecting Latent Prints Latent print Impression left when a person touches an object with their fingers Latent prints are an extremely valuable piece of physical evidence as it can link individuals to crime scenes Unknown deceased individuals can also have their fingers examined to provide a positive identification Guidelines: Always wear gloves Package in heat-sealable plastic bags Zip tie the items to minimize movement  Collection of Glass Evidence Glass evidence can be analyzed to determine if it originated from the same source, the direction of force and the sequencing of blows Glass can also be reconstructed to the object it used to be If possible and enough of a sample Guidelines: Submit in leakproof containers Film canisters, plastic pill bottles Do NOT use paper or glass containers Label glass “inside” or “outside” Vacuum glass particles if possible  Collection of Controlled Substances Controlled Substance a drug whose manufacture, possession, or use is regulated by the government Possession of illegal drugs is one of the most common arrests law enforcement will conduct during their career Special care is taken as not to ingest, inhale or contact illegal drugs as overdoses can occur Guidelines: Always wear gloves Wear a mask as not to inhale powders Immediately call for medical help if contaminated Separately package multiple bags of drugs  Collection of Arson Evidence Arson Intentionally setting a fire in a criminal act Arson examinations can determine the presence of ignitable liquids Labs can identify gasoline, fuels, and unique solvents Evidence to Look for: Candles, cigarettes, matchbooks, Molotov cocktails Burn trails On cloth, paper, carpet, hardwood floors Guidelines: Must be in airtight containers Paint cans are the best Leave 3 inches of space at the top  Collection of Document Evidence Questioned Documents any signature, handwriting, typewriting, or other mark whose authenticity is in dispute or doubtful Guidelines: ***Must be in condition it was found*** Must not be unnecessarily: Folded Torn Marked Stamped Soiled Handled excessively  Chain of Custody Chain of Custody Chronological documentation of custody, transfer, analysis and storage of evidence Evidence must be strictly accounted for as to avoid allegations of tampering, planting and cross-contamination For law enforcement, evidence is kept in a sealed and organized evidence room Documentation Needed: Date and time sealed Case number Persons of interest Offense Name of person sealing it