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Forensics CHS McNiff

Forensics CHS McNiff. Vocabulary. CRIME SCENE: Any physical location in which a crime has occurred or is suspected of having occurred. PRIMARY CRIME SCENE: The original location of a crime or accident. SECONDARY CRIME SCENE: An alternate location where additional evidence may be found.

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Forensics CHS McNiff

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  1. Forensics CHS McNiff

  2. Vocabulary • CRIME SCENE: Any physical location in which a crime has occurred or is suspected of having occurred. • PRIMARY CRIME SCENE: The original location of a crime or accident. • SECONDARY CRIME SCENE: An alternate location where additional evidence may be found.

  3. Vocabulary • SUSPECT: Person thought to be capable of committing a crime. • ACCOMPLICE: Person associated with someone suspected of committing a crime. • ALIBI: Statement of where a suspect was at the time of a crime. • VICTIM: a person who suffers from a destructive or injurious action or agency.

  4. Processing Versus Analysis • Crime scene investigations have two aspects: processing & analysis • Processing follows a series of standards steps

  5. Types of Scenes • Two major categories of criminal activities having crime scenes: • property crimes (larceny, burglary, auto theft) • crimes against persons (assault, battery, sexual assault, robbery, murder)

  6. Types of Scenes • The nature of the scene will affect the way it is handled: • indoor or outdoor • public or private property

  7. Initial Actions & Scene Security • Initial actions of the first responders include: • Rendering aid and assistance to the victim • Arresting any suspects • Detaining any witnesses • Noting initial scene conditions • Securing the scene

  8. Initial Actions & Scene Security • Crime scene security is needed to preserve the integrity of the scene • Once the exigent emergency situation is resolved, subsequent actions at the scene will require a warrant • Duties and Responsibilities of the First Responders at the Crime Scene

  9. Secure & Isolate the Crime Scene • First priority is medical assistance to individuals & arresting the perpetrator. • Ropes or barricades and guards will prevent unauthorized access to the area. • Every person who enters the crime scene has the potential to destroy physical evidence.

  10. Secure & Isolate the Crime Scene • The lead investigator evaluates the scene & determines the boundaries. They do an initial walk through & develop a strategy. • All items must be documented & photographed.

  11. Steps in Scene Processing & Analysis • Scene Survey & Evidence Recognition • Scene Searches • Documentation • Evidence Collection & Preservation • Release of the Scene

  12. Scene Survey & Evidence Recognition • A scene survey is an initial walk-through to establish the type of scene, note any transient evidence, and recognize any potential physical evidence • Transient evidence is evidence that is easily destroyed or compromised

  13. Scene Survey & Evidence Recognition • Evidence recognition is the determination of which physical evidence is relevant to the case as opposed to being part of the background

  14. Systematic Search

  15. Sketches • Once photos are taken, sketch the scene.

  16. Sketches • A rough sketch is a sketch, drawn at the crime scene, that contains an accurate depiction of the dimensions of the scene & shows the location of all objects having a bearing on the case. • All measurements are made with a tape measure • Show all items of physical evidence • Assign each item a number or letter and list it in the legend • Show a compass heading designating north

  17. Rough-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com.

  18. Sketches • A finished sketch is a precise rendering of the crime scene, usually drawn to scale. • Computer-aided drafting (CAD) has become the standard.

  19. Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com.

  20. Notes • Note taking must be a constant activity throughout the processing of the crime scene. • The notes may be the only source of information to refresh memory. • Tape-recording notes at a scene can be advantageous – detailed notes can be taped much faster than they can be written.

  21. Searching the Crime Scene • One person should supervise & coordinate. • Include all probable entry & exit points in search

  22. Searching the Crime Scene Ypsilanti Township, MI are looking for a burgundy vehicle in connection with a hit-and-run accident that critically injured an 11 year-old boy • What to search for will be determined by the particular circumstances of the crime. • Examples • Homicide • Hit-and-run

  23. Collect Physical Evidence • Physical evidence can be anything from massive objects to microscopic traces. • It may be necessary to take custody of all clothing worn by the participants in a crime. • Handle carefully & wrap separately to avoid loss of trace evidence.

  24. Collect Physical Evidence • Critical areas of the crime scene should be vacuumed & the sweepings submitted to the lab for analysis. • Mobile crime-scene vehicles carry supplies to protect the crime scene; photo, collect, & package evidence; & develop latent fingerprints.

  25. Collect Physical Evidence • The integrity of evidence is best maintained when the item is kept in its original condition as found at the crime scene. • The entire object should be sent to the lab. • If evidence is found adhering to a large structure, remove specimen with forceps or other appropriate tool.

  26. Collect Physical Evidence • In the case of a bloodstain, one may either scrape the stain off the surface, transfer the stain to a moistened swab, or cut out the area of the object containing the stain.

  27. Collect Physical Evidence • Each different item or similar items collected at different locations must be placed in separate containers. • Packaging evidence separately prevents damage through contact and prevents cross-contamination.

  28. What evidence would you collect? Mock Crime Scene: http://www.masss.gov

  29. fingerprints • Fingerprints latent (hidden) or visible • Fingerprints of Francisca Rojas, the first person convicted of murder through the taking of fingerprint evidence card contains the fingerprints of Francisca Rojas, the first person convicted of murder through the taking of fingerprint evidence.

  30. Post Mortem Interval • The use of post mortem changes to estimate the time of death.

  31. Forensic pathology • Forensic pathology is a branch of pathology concerned with determining the cause of death by examination of a corpse. • The autopsy is performed by the pathologist at the request of a coroner or medical examiner usually during the investigation of criminal law cases and civil law cases in some jurisdictions.

  32. Impressions • Tire markings, shoe prints depressions in soil, bite marks

  33. Tool marks • The goal of toolmark analysis is to determine if a particular tool produced a particular mark. 

  34. Hair & fibers • Any animal or human hair present that could link a person to a crime.

  35. Firearms & ammunition • Any firearm • Cartridge or round Phil Spector

  36. Glass • Particles of glass transferred to a person or object during a crime.

  37. Fire Debris analyses • Fire Debris Analysis involves the determination of whether or not added accelerant residues are present in samples obtained from fires.

  38. Explosives • Any devise containing an explosive charge. • Also all the material removed from the area of detonation. World trade center bombing

  39. Murrah Building - April 19 1995

  40. Soil & vegetation • In forensic science, soil and vegetation are frequently encountered as trace evidence and can be used to link suspects, cars to a crime scene

  41. Drugs • Is any substance that, when absorbed into the body of a living organism, alters normal bodily function • Any substance seized in violation of laws regulating the sale, manufacture, distribution, and use of drugs

  42. Growing Marijuana in the Basement bsapp.com

  43. Bags for sale bsapp.com

  44. bsapp.com

  45. Clandestine labs • Clandestine drug laboratories (clan labs) are facilities equipped and used in the production of illegal drugs.

  46. Documents • Authenticating source • Handwriting analysis • Typewriting • Ink • Paper

  47. Paint • Paint samples can be used to link vehicles, boats,… to a crime scene • Paint transfer from a vehicle to a struck pedestrian may be the only source of evidence linking the suspect to the crime scene.

  48. Serology • Liquid or dried: on fabrics, objects surfaces, … • Can be used to determine Identity: perpetrators and victims. • Can help reconstruct the crime. Found on the Hike and Bike Trail in Texas

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