CSCI 130 Forensic Computing CJ Notes Structure and Conduct of Investigations

I.Types of investigations a. Reactive: action taken after a crime has been reported b. Proactive: action taken to prevent a crime, to prevent further crimes, to stop on-going criminal activity

II.Reactive Investigations a. Involve discovery of offense, preliminary investigation, and follow-up investigation b. How activities structured varies by agency; some activities are more structured in some agencies, as in large agencies

III.Preliminary investigation a. Often done by responding patrol officer who reports findings to investigators b. Serious cases will see investigators doing preliminary as well as follow-up c. Involves such tasks as: preserving scene; identifying evidence and witnesses

IV.Follow-Up Investigation a. Agency policy determines extent and nature of follow-up b. Solvability factors play important role: 1. any evidence that will lead to or is likely to contribute to identifying the suspect or substantially increases the chances of doing so 2. witnesses who can identify suspect

3. witnesses who can provide license plate; vehicle description 4. fingerprints; DNA sources; blood; body fluids; shoe prints; discarded or torn clothing 5. other evidence that can identify the suspect

c. Detectives perform many duties between arrest and court 1. re-interview witnesses 2. collect additional evidence 3. attend to the victim; victim’s family

4. attend meetings with prosecutor; supervisors for updates 5. assist/meet with area agencies re: similar offenses 6. other duties directed toward successful prosecution

V. Investigators must have a working knowledge of law a. Search and seizure b. Confessions; statements c. Rules of evidence

Types of Evidence A. Real - physical details and objects, such as murder weapon, stolen property, fingerprints, DNA 1. May be original objects or facsimile representations, such as photographs, casts of tire tracks, footprints, or other duplicates of unavailable/unusable items in their original form

B. Testimonial – the sworn, verbal statements of witnesses 1. All real evidence is accompanied by testimonial evidence given by one qualified to discuss it 2. Not all testimonial evidence is accompanied by real evidence, however

C. Direct evidence – eyewitness evidence 1. Testimony from a witness that she saw a person painting a fence is direct evidence 2. Testimony from a witness as to what he heard; gunshots, threats made

D. Circumstantial – also called indirect evidence 1. Evidence from which a fact can reasonably be inferred 2. A person was seen carrying a paint can and brush one block from a newly painted fence 3. Circumstantial evidence that the person painted the fence.

d. Probable cause for the arrest (Facts or circumstances that would lead a reasonable and prudent person to believe a crime has been committed and the suspect committed it) is a lower level of proof than that needed for conviction (Proof beyond a reasonable doubt)

VI.Factors that influence whether a crime will be solved include: a. Timeliness of initial police response b. Collection of evidence c. Delay in reporting crime

d. Investigator(s) competence; agency resources e. Competence and cooperation of patrol officers f. Complexity of the case

VII. Factors that militate against convictions a. Lack of evidence, not present or overlooked b. Poor presentation of case c. Poor case preparation

d. Jury nullification e. Non-sympathetic victim resulting in weak case f. Jury assessment of victim culpability

VIII. Information and Evidence a. Information is the lifeblood of any investigative effort. b. All evidence is information but not all information is evidence.

Conclusion IX. The work is seldom done a. New evidence b. New witnesses c. Re-visit evidence; witness statements