This document provides an overview of law enforcement procedures for criminal investigations, including preliminary investigations, securing crime scenes, collecting evidence, and forensic analysis techniques. It discusses protocols for responding to and documenting crime scenes, as well as collecting trace evidence like fingerprints, ballistics, and DNA. Advanced technologies like AFIS, NIBIN, and superglue fuming have improved the ability to identify suspects and link crimes through physical evidence analysis.

1. Law Enforcement Criminal Investigations Part One

2. Preliminary Investigations Recall from our discussion on Uniformed Patrol – the Alternative Strategy of Retroactive Investigation of Past Crimes by Detectives If the call involves a crime, the officer conducts a preliminary investigation and often refers the case to a detective who then conducts a follow up investigation of the crime

3. Crime Scene A location that may contain evidence of a crime.

4. Crime Scenes A search of an offender’s home may yield evidence, but not be the location the crime occurred. Protocols for scene protection, documentation and evidence recovery are critical at all crime scenes

5. Initial Response Note/log information Be aware of any persons or vehicles leaving. Approach the scene cautiously, scan the entire area to thoroughly assess the scene, and note any possible secondary crime scenes . Be aware of any persons and vehicles in the vicinity that may be related to the crime. Make initial observations (look, listen, smell) to assess the scene and ensure officer safety before proceeding. Remain alert and attentive. Assume the crime is ongoing until determined to be otherwise. Treat the location as a crime scene until assessed and determined to be otherwise.

6. Officer Safety The safety of officers and others, in and around the crime scene, is the first responder’s responsibility. After controlling any dangerous situations or persons, the next responsibility is ensuring medical attention is provided to injured persons while minimizing contamination of the scene.

7. Securing the Scene Boundaries of the scene start at a focal point, such as a body or point of entry and extend outward to include: Where the crime occurred. Potential points and paths of exit and entry of suspects and witnesses. Places where the victim/evidence may have been moved.

8. Crime Scenes Evidence tends to deteriorate Investigator’s often refer to the “golden hour;” the time when evidence is best recovered. Some jurisdictions are taking the crime lab to the crime scene Photographs provided by OBS INC., Specialty Vehicles

9. Evidence Collection Proper protocols and techniques for collecting evidence are very specific and critical. Generally, first responders preserve scenes and trained specialist collect and analysis evidence

10. Evidence Collection Chain of Custody Testimony and documentation that details the location and condition of evidence from seizure to trial. It assures the court that items entered into evidence are in the same condition as when they were seized. The chain of custody and the procedures used to analyze evidence are more often challenged than the science behind the analysis.

11. Forensic Science and Criminalistics Forensic comes from the Latin word "forensis," meaning "of the forum," where the law courts of ancient Rome were held Forensic science is the application of any type of science, biological, social, physical or mathematical to legal matters.

12. Forensic Science and Criminalistics Forensic Science is the broader term, meaning the part of the science used to answer a legal question. Toxicology, ondontology, accounting, pathology, serology Criminalistics is a branch of Forensic Science dealing with the study of physical evidence related to a crime.

13. Daubert Test In order for the analysis of evidence to be used against a defendant, the court must accept the scientific conclusion as valid. The standard for accepting scientific analysis is the Daubert Test – from Daubert v Merrel Dow Pharmaceuticals, inc.

14. In the Daubert Test The Court asks - Is the science derived by the scientific method? Has the science been subjected to peer review or publication? Does the relevant scientific community generally accept the science? What is the error rate of thee scientific technique used to gain the information? Are there standards for controlling the technology used to obtain the scientific evidence?

15. Transfer Theory Edmund Locard, a French Scientist developed the theory that contact between individuals or objects results in a transfer of material between them.

16. Trace Evidence Hair Fiber Glass Paint Dust Dirt Chemicals Firearms Fluids Blood Bite Marks Shoe Prints Tool Marks Wounds Documents Fingerprints

17. The First Major Systems of Personal Identification Anthropometery exact measurements of an individuals body yields a characteristic formula for comparison. Dactlography Fingerprints

19. The West Brothers case is attributed to the ascendancy of fingerprints over other means of personal identification

20. A 1924 Act of Congress established the FBI Identification Division By 1946 they had 100 Million Fingerprint cards

21. Henry Classification System

22. Lifting Prints Plastic – Found in a soft surface like wax, paint or putty. Visible – Contact with a wet fluid like blood. Latent – Meaning “Hidden” These prints are left by the oils secreted by our hands and are generally not visible.

23. Dusting for Prints Powders have different properties, for instance color. Common colors are black, white, gray, aluminum, red, and gold. Color is selected to make the best contrast between the print and the surface. For instance , a white powder might works best on a dark surface .

24. A utomatic F ingerprint I dentification S ystem

25. AFIS A combination of hardware and software used to scan and classify fingerprints so that they can be stored in a database. There are several regional, state and local AFIS databases: Western Identification Network Arizona DPS Ontario, CA police Department

26. Integrated Automated Fingerprint Identification System National fingerprint and criminal history system maintained by the Federal Bureau of Investigation (FBI), Criminal Justice Information Services (CJIS) Division.

27. AFIS Maintains the largest Biometric database in the world, containing the fingerprints and corresponding criminal history information for more than 47 million subjects. The fingerprints and corresponding criminal history information are submitted voluntarily by state, local, and federal law enforcement agencies.

28. Biometrics The science of automatically identifying individuals based on a physiological or psychological characteristic: Fingerprint Retinal Scan Voice Print Facial Scan Thermal Image Handwriting, gait, and others

29. Returning to IAFIS IAFIS provides FIVE services: Ten-Print Based Fingerprint Identification Services Latent Fingerprint Services Subject Search and Criminal History Services Document and Imaging Services Remote Ten-Print and Latent Fingerprint Search Services

30. Fingerprint Advances The recovery of latent (hidden) fingerprints is not longer restricted to powder: Superglue fuming Laser applications Unique powders Technology has advanced to the point wherein some jurisdictions use superglue fuming wands at the crime scene

31. Fuming There are several types of fuming, the most recent is “ super glue fuming.” Super glue contains the chemical Cyanoacrylate. When heated this substance sticks to trace oils, hardens and when dry it is visible.

32. Ballistics Class Characteristics are identified by lands. Individual Characteristics are identified by striations

33. Firearms Identification

34. National Integrated Ballistic Identification System In 1993, prior to NIBIN’s, the FBI (DRUGFIRE) and ATF (BULLETPROOF/CEASEFIRE) established separate computerized ballistics imaging systems. NIBIN was established in 1997 to unify these systems. There are currently over 220 crime labs participating.

35. Criminal Investigations Part I Find more police books at www.police-writers.com