1 / 14

Criminal Investigations

Criminal Investigations. The Crime Scene ID Suspect Informants. Criminal Investigations. The goal of criminal investigations is not simply to catch criminals. Investigators must also collect evidence that can be used in court to convict them Innocent until proven guilty

moshe
Download Presentation

Criminal Investigations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Criminal Investigations The Crime Scene ID Suspect Informants

  2. Criminal Investigations • The goal of criminal investigations is not simply to catch criminals. • Investigators must also collect evidence that can be used in court to convict them • Innocent until proven guilty • Two of the most common investigatory techniques are searches and interrogation

  3. The Crime Scene • Secure the Crime Scene • Usually handled by the Patrol Officer • Pursue and arrest suspect • Call detectives if needed • Document the Crime Scene • Take statements from witnesses • Note conditions at the time of crime • Take pictures and identify objects • Build Case File • All documentation taken at the crime scene • Physical evidence taken to evidence room • Chain of Custody is established • Each new person who takes custody of the case must also write the date and time and sign it. • Each custodian may be called during a trial

  4. ID Suspects • If people witness a crime, detectives will try to get them to identify the suspect. • Three methods of for witness to identify suspects: • Line up • Show up • Throw down *These methods can be suggestive

  5. Bell Ringer 11/12/13 • What was the policing strategy that was placed in New York? Briefly explain, did it work? • What was the policing strategy that was placed in San Diego? Briefly explain, did it work? • What happen in Houston?

  6. Informants • Many police officers develop a network of informants, who give intelligence about what is going on in the criminal community • Most informants are low level criminals • Police commonly use informants to get search warrants • Informants usually ask for something in return • Cash

  7. Informant Reliability • Most informants are criminals • Reliable • Say what they are told • Trying to get out of trouble • Jail-house informants • SC has ruled that police cannot deliberately elicit incriminating statements from indicted defendants without an attorney • If cellmates without prior police contact offer information to police, it can be used in court. * Police defend the use of informants as a necessary evil

  8. Crime Labs • More than 300 accredited crime labs exist • The FBI operates the nations largest, which examines evidence from other federal, state, and local agencies as well as from FBI cases. • The FBI divides the crime lab into units each specializing in one area: • Trace Evidence Unit • Questioned Documents Unit • The Firearms and Toolmarks Unit • The Latent Print Unit • DNA Analysis Unit

  9. Trace Evidence Unit Examines: hairs, fibers, ropes, cordage, feathers, plants, woods, soils, glass, and building materials Find traces of material and compare against what they have on file Can match fibers to clothing as well as color, length and style of hair

  10. Questioned Documents Unit • Studies anything that has to do with paper. • From determining what a piece of paper is made of to analyzing handwriting and breaking codes. • Deals with machines that use paper. • Also handles footprints and tire tracks • Maintains collections of anonymous letters, bank robbery notes, fraudulent checks, office equipment, shoe prints and tire tracks.

  11. Firearms and Toolmarks Unit Investigates guns, ammunition, evidence with residue from gunshots, tools, motor vehicles numbers and serial numbers. Maintains a collection or firearms, ammunition and their distinctive markings Ballistics experts can tell what kind of a gun fired a bullet.

  12. Latent Print Unit Analyzes fingerprints Everyone has fingerprints, and they remain the same throughout life. Since 1924, the FBI has had a fingerprint unit. Now also look for fingerprints, palm prints, foot prints and even lip prints They use lasers, alternative light sources, chemicals as well as powders. The FBI’s Automated Fingerprint Identification System is used by all to match prints

  13. The DNA Analysis Unit The genetic code that determines a person’s physical characteristics. Each human cell holds the complete genetic blueprint for each individual DNA is compared from suspect to DNA found at the crime scene

  14. Bell Ringer 11/13 • What are the Miranda Rights? • What does it mean to be in custody?

More Related