Xã hội học - Follow - Up investigation

Establishing the existence of a violation Obtaining probable cause for a search warrant Apprehending violators in the commission of illegal acts Identifying the violators’ associates Verifying informant reliability

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SIXFollow-up InvestigationLEARNING OBJECTIVESSummarize the factors used to determine whether a follow-up investigation is neededOutline common internal and external sources of case informationExplain the techniques used in neighborhood and vehicle canvassesDiscuss the role and use of informantsUnderstand the purpose and objectives of surveillanceBe familiar with the practice of polygraph and psychological-stress evaluatorsDescribe the methods for conducting photo and live lineupsExplain the guidelines for recording identification results6-1INVESTIGATIVE SOLVABILITY FACTORSCan the identity of the suspect/s be established through: Useable fingerprints being discovered Significant physical evidence being locatedVictims/witness/informant information A license number of or a significant description of the vehicle known to have been used in the offense6-2(a)INVESTIGATIVE SOLVABILITY FACTORS (cont'd)Is there serious physical harm or threat of serious physical harm to the victimDid the suspect(s) utilize a deadly weapon or dangerous ordinanceIs there a significant m.o. which will aid in the solution of the offenseIs it a sex offense in which the victim and suspect(s) had physical contact6-2(b)INVESTIGATIVE SOLVABILITY FACTORS (cont'd)Can a suspect be namedCan a suspect be identifiedCan a suspect be describedIs there another reason which leads you to believe that the offense should be assigned for a follow-up investigation6-2(c)BURGLARY SCREENING DECISION MODELOne of the more useful tools used by investigators at the onset of their effort is a decision model form.This allows them to objectively make decisions with regard to how best to proceed with their investigative work.6-3COMMON INTERNAL SOURCES OF CASE INFORMATIONIncident and supplemental reportsPhysical evidence seizedJail booking reportsField interview/information reportsInventories of impounded vehiclesTraffic citationsCrime lab reportsThe neighborhood and vehicle canvasses6-4FIELD INTERVIEW/INFORMATION REPORTSA field interview/information card (FIR) is filled out when patrolling officers identify persons or vehicles that are suspicious to them but are not connected to any particular offense.6-5(Source: Courtesy Springfield, Missouri, Police Department)NEIGHBORHOOD CANVASSA fundamental aspect of most investigations is the neighborhood canvassThe investigator contacts residents, merchants and others in the immediate vicinity of the crimeA systematic neighborhood canvass soon after the crime may be useful in twenty percent of the casesThe extent of the canvass depends on:The type of offenseThe time of dayThe characteristics of the crime scene6-6NEIGHBORHOOD CANVASS FORMThis form provides the investigator with:A list of persons contactedInvestigation notes for later analysisA source of potential leads6-7(Source: Courtesy Imprimus Forensic Services, LLC)INFORMATION NEEDED BEFORE CONDUCTING A NEIGHBORHOOD CANVASSAll information relating to the offenseA full description of the suspectAny injury sustained by the suspectThe type of property taken6-8(a)INFORMATION NEEDED BEFORE CONDUCTING A NEIGHBORHOOD CANVASS (cont'd)Possession of these facts is essential for:Officer’s safety For the intelligent questioning of possible witnesses6-8(b)INFORMANTSInformation provided by informants often plays a vital role in a successful investigationSuch information may provide evidence of an unreported crimeSuch information may provide the basis for a search warrantSuch information may constitute the basis for an arrest6-9MAJOR CATEGORIES OF INFORMANTSMercenary informant - information provided for financial rewardRival informant - information provided to establish monopolistic control over activity in question by eliminating a competitorPlea bargaining informant - information provided to obtain reduced charges or lenient sentence for informationSelf-aggrandizing informant - information provided to obtain enhanced sense of self-importance6-10(a)MAJOR CATEGORIES OF INFORMANTS (cont'd) Fearful informant - information provided because they are worried they will be endangered by the criminal activities of an associateFalse informant - information provided is misleading to direct the investigation away from her/himself, friends, and relativesAnonymous informants - information provided by an unknown personLegitimate informants - information provided by a law abiding citizen out of a sense of civic duty6-10(b)EFFECTIVE USES OF SURVEILLANCE Establishing the existence of a violationObtaining probable cause for a search warrantApprehending violators in the commission of illegal actsIdentifying the violators’ associatesVerifying informant reliability6-11(a)EFFECTIVE USES OF SURVEILLANCE (cont'd) Providing protection for undercover investigators or informantsLocating persons, places, or thingsPreventing crimeGathering intelligence of individuals and premises prior to the execution of a search warrantGathering intelligence on illegal groups' activities6-11(b)AREA UNDER VIDEO MONITORINGThe use of video surveillance camera in public places is becoming commonSuch systems may deter crimeVideo systems may also gather evidence of a crime6-12(Courtesy © Scott Iskowitz and Tampa Tribune)POLYGRAPH EXAMINATIONSThese examinations are used to:verify, corroborate, or refute statements made by victims, witnesses, and suspectsobtain additional investigative leadsnarrow or focus the investigation eliminate suspects6-13THE POLYGRAPH The polygraph is designed to record physiological changes in:Respiratory rateBlood pressure and heart rateAmount of sweat on the fingertips6-14POSED POLYGRAPH EXAMThe polygraph is an investigative toolIt does not substitute for a proper investigationOnly certified, well trained polygraphists should be used6-15(Courtesy Lafayette Instrument)PSYCHOLOGICAL-STRESS EVALUATOR (PSE) AND COMPUTERIZED VOICE-STRESS ANALYZER (CVSA)The PSE and the CVSA measures voice fluctuationsThese fluctuations can indicate stress.They can also reveal deceptionRecordings of phone conversations can be used in place of personal contact with a suspect6-16PROCEDURES FOR PHOTO LINEUPSInclude only one suspect in each identification procedureSelect “fillers” (nonsuspects) who generally match the witness’ description of the perpetratorIf multiple photos of the suspect are available, use the one made closest to the time when the crime was committedLineups should include a minimum of five fillersIf there are multiple witnesses, consider placing the suspect in different positions each time a lineup shows to a witness6-17(a)PROCEDURES FOR PHOTO LINEUPS (cont'd)If a new suspect is developed, avoid using fillers which have been used in a previous lineup for the same witnessMake sure that no writing or information about the suspect's previous criminal history can be seen by the witnessBefore the witness views the lineup, check again to make sure the suspect doesn’t unduly standoutRecord the presentation order or the lineup and handle the original photographs as evidence Write a supplemental report which chronologically describes what happened6-17(b)WITNESS LINEUP IDENTIFICATION FORMInvestigators carefully document witness responses to a live lineup by using this formNote the names of the witness, the officer, the prosecutor and the defense attorney all appear on the form6-18(Source: Courtesy St. Petersburg, Florida, Police Department)RECORDING IDENTIFICATION RESULTSProper documentation includes:check to make sure that all signatures need for the various forms are completed;collect the information needed to complete standard forms prior to conducting the lineup procedure;if another witness will have contact with any photographs or forms, make sure that the previous witness has not made any marks or comments on them; andinclude in the supplemental report a record of both identification and non-identification results, including any statements as to how sure, or unsure, the witness is6-19AUTOMATED PHOTO LINE UPToday investigators may use automated photo-line up programsWitness descriptions are entered into the computerThe computer searches the database of suspects and persons with similar physical characteristics6-20(Courtesy of TFP, Inc.)

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