Investigations: Leads and Informants

Known Identity versus Unknown Identity

  • A known identity is one where the perpetrator is known and has been named by the victim or witnesses.
  • All other cases are of unknown identity.
  • Challenge the skill of the investigator: known-identity cases constitute a high percentage of cases cleared by arrest in any police agency.

Basic Leads: Overview

  • Basic Leads are initial leads offered by the victim or observed during investigation.
  • Developing leads is a combination of know-how, the cognitive process, and an ability to work rapidly.
  • Motive and opportunity are broad areas of investigation basic to any crime.

Basic Leads: Known Identity vs Unknown Identity (Continued)

  • In cases of known identity, the objective is to corroborate the eyewitness story.
  • In cases of unknown identity, the objective is to develop suspects by following the basic investigative leads with the goal of identifying the perpetrator.

Basic Leads: Active vs Passive Information

  • Active information:
    • Leads to the establishment of a group of suspects.
    • The strength of the information against each member depends on the nature of the evidence, but it may indicate prime suspects.
  • Passive information:
    • Associative evidence that can be of use only if a group of suspects has been developed.
    • Often confirms suspicions against a person as a prime suspect by associating him or her with the crime scene or the victim.

Basic Lead: Victim's Background (Questions to Generate Leads)

  • Is there anything significant about the victim that would contribute a basic lead?
  • Did the victim know the perpetrator?
  • Does the victim suspect any person?
  • Has the victim a history of crime?
  • Did the victim have a weapon?
  • Has the victim an aggressive personality?
  • Has the victim been the subject of any field contact reports?
  • What is the license number and description of the victim's car?
  • Was the victim mistaken for someone else?

Basic Lead: Victim's Background (Continued)

  • Has the victim an aggressive personality?
  • Has the victim been the subject of any field contact reports?
  • What is the license number and description of the victim's car?
  • Was the victim mistaken for someone else?

Figure 6-1

  • Basic Leads Are the Link between What Happened and Who Did It.

Basic Lead: Benefit

  • Who might benefit from a crime?
  • In homicides, the relationships between the victim and persons who might benefit from the fact of death are productive in providing significant leads.

Basic Lead: Opportunity

  • An admitted or suspected presence at the crime scene is a lead.
  • When an offender knows they are suspected of being at the crime scene, they often fabricate an alibi (claim of being elsewhere).
  • Investigating the alibi serves to discredit or credit the alibi/opportunity.

Basic Lead: Knowledge

  • Knowledge necessary for committing the crime:
    • In theft, who might know their way about the premises and about the presence and location of articles of value.
    • In armed robberies, who knew the routine of the victim or the business.
  • Persons who have access to the premises at which the crime occurred or who are familiar with them.
  • Persons who knew of the value and place of storage of property or the routine of the victim or the business victimized.
  • Any present/former employee or spouse; service and maintenance personnel; neighbors; criminals with contacts among the knowledge holders.
  • Persons noticed in the area recently who were acting strangely (e.g., sex cases, fires, homicides) or applying for work, soliciting sales, conducting surveys, etc.
  • Knowledge also means having the skill and capacity to commit the crime.

Field Contact Reports

  • Field contact reports are an aggressive police patrol tactic.
  • They record the names and descriptions of persons coming to police attention and the time, date, and place they were seen and interviewed.
  • These reports are confidential and not disclosed to the public.
  • They represent a broad surveillance technique.

Basic Lead: Vehicles

  • There is no better clue to the identity of a criminal than the identification of a vehicle.
  • Even a fragmentary description is helpful.
  • Motor vehicle records may contain a thumbprint or a photograph or both, usually have some physical description of a licensed operator.

Basic Lead: Weapons

  • Firearms are marked with the maker's name and a serial number, and their ownership often can be traced through sales and registration records.
  • The ownership of knives can often be identified.

Basic Lead: Fingerprints

  • Fingerprints are a high potential for identifying perpetrators of crime.
  • Computerized fingerprint searching systems permit rapid scanning of thousands of fingerprint records.
  • Crime-scene fingerprints are determined to be of value or of no value.
    • Imprints of value have an adequate number of identifying characteristics.
  • Crime-scene fingerprints are compared with the imprints of persons who are legally at the scene (victim, witnesses, police, other known visitors).
  • Fingerprints on file are searched to identify the suspect and match them to crime-scene fingerprints.
    • Request search
    • Single-digit search
    • Cold search
  • Fingerprints linking a suspect to a crime scene are a significant lead.

Basic Lead: Stolen Property

  • A search for stolen property is a search for identifiable items.
  • Investigators should check pawnshops, secondhand dealers, junk shops, and other places where stolen property is likely to be offered for sale.
  • Computer records will allow for searches of persons who frequently sell or pawn used property.

Basic Lead: Modus Operandi

  • Modus operandi (MO) is the choice of a particular crime to commit and the selection of a method of committing it.
  • Signature: the distinctive, personal aspects of the crime that reveal the offender.
  • MO file: a file that catalogs past MO patterns to compare with current crimes.
  • Identifying a perpetrator by MO in past crimes that fit the facts of the crime being investigated.

Computer Databases

  • Can be local, state, regional, or national.
  • National Crime Information Center (NCIC): Operated by the FBI; serves law enforcement in the US, Canada, and Mexico; covers wanted/missing persons, stolen property.
  • Approximately 2.5 imes 10^6 inquiries per day.
  • National Integrated Ballistic Information Network (NIBIN): Maintained by ATF; compares gun evidence.

Offender Registration

  • State sex offender registries created from the Jacob Wetterling Act (1994).
  • All states have sex offender registration laws.
  • California was the first state in 1947.
  • Registration can include name, address, DOB, physical description, fingerprints and photograph.
  • Length of time for registration varies by jurisdiction.

Photographs of Known Criminals

  • Mug shots and mug books are often prepared for specific offenses.
  • As long as the photographs show several suspects of various types and origins, this practice does not destroy the validity of future testimony of witnesses.

Composite Sketches

  • Victim and witnesses may collaborate with a police artist.
  • Identi-Kit system: plastic slides containing photo reproductions of small portions of a human face.
  • Computer software and facial recognition software are now available.

Injured Suspects

  • Injured suspects may be a basic lead.
  • In most states, physicians are required to report gunshot or knife wounds when patients seek treatment.

Linkage Between Suspect and Crime Partners

  • Six types of relationships that form strong personal linkages between persons engaged in criminal activity:
    • Neighborhood friendships
    • Juvenile hall and prison contacts
    • Family relationships
    • Co-ethnic contacts
    • Buyer-seller interactions
    • Lovers
  • "Better him than me" mentality describes some partner dynamics in criminal activity.

Social Media

  • Social media sites contain a wealth of information which may be important to an investigation.
  • Platforms such as Facebook, MySpace, and Twitter are useful basic leads.
  • Used to find pictures of suspects, witnesses, and victims.
  • Aids in locating stolen items.

Video Surveillance and Cell Phones

  • Video surveillance cameras are now capable of broadcasting live via the Internet.
  • They are cheaper, more widely installed, and provide better quality pictures.
  • Cell phones contain a wealth of information: contacts, calendars, notes, messages, photos, geographical information, web browsing sites, and social networking.

Informants

  • Informants are a means through which basic leads can be developed.
  • Basic-lead informants: reasons include citizen's duty to divulge information, to get rid of a competitor, jealousy and revenge, and seeking pay for information.

Informants: Participant Informants

  • Act as a go-between in illegal drug sales.
  • Aims: identify the drug seller and introduce the undercover investigator as a potential buyer.
  • Flipped: an arrestee turned to work for the police.

Informants: The Special Employee

  • A paid person because of knowledge of the drug scene and relationships among local dealers.

Informants: Covert Informants

  • Report information to the police about a terrorist or other criminal organization from within the group (moles).
  • Placed in long-term roles.

Informants: Accomplice Witnesses

  • A person liable to prosecution for the same offense charged in the trial.
  • May be offered leniency in exchange for cooperation or granted immunity.
  • Witness protection program.

Investigative Techniques

  • Surveillance is the observation of people and places by investigators to develop investigative leads.

Investigative Techniques: Visual Surveillance

  • Fixed visual surveillance (stakeout, plant).
  • Moving visual surveillance (a tail).
  • Often use two- or three-person surveillance teams.
  • Global positioning device (GPS).

Investigative Techniques: Audio Surveillance

  • Wiretapping and electronic eavesdropping.
  • Bugging places or people for sound.
  • Dalia v. United States (legal precedent referenced).
  • Participant monitoring involves one person consenting to being recorded.
  • Debugging detects bugging.

Investigative Techniques: Contact Surveillance

  • Dyes stain a person's hands or clothing to prove a connection between the stained person and the object under surveillance.
  • Ultraviolet light can be used.
  • Supplements visual surveillance.

Search Warrants

  • Guided by the Fourth Amendment: right against unreasonable searches and seizures; warrants must issue upon probable cause and describe place to be searched and persons or things to be seized.

Search Warrants: Probable Cause Standard

  • Must demonstrate to the judge or magistrate that a crime has occurred, or is occurring, and that evidence relative to that crime will be found at a particular location.

Police Intelligence: Criminal Investigation Information

  • Intelligence is the secret or clandestine collection and evaluation of information about crime and criminals not normally available through overt sources.
  • Criminal investigation information is police intelligence oriented toward the solution of ongoing investigations.
  • The intelligence process is cyclical.

Police Intelligence: Six (Seven) Stages

  • Needs
  • Collection
  • Evaluation and collation
  • Analysis
  • Interpretation
  • Dissemination
  • Reevaluation
  • Note: The slide lists seven stages (Needs, Collection, Evaluation and collation, Analysis, Interpretation, Dissemination, Reevaluation) under the heading of six stages, illustrating a minor discrepancy in the original text.

Criminal Investigation Information Center

  • Aids police agencies by reviewing and collecting information common to police reports.
  • Provides information in response to investigators’ requests.
  • Organizes information on criminal activities in other jurisdictions to connect it to local crime activities.
  • Arranges information sharing between investigators and investigative units.

Police Intelligence: Undercover Police Agents

  • Often preferable to using an underworld informant.
  • Many police units use young recruits fresh from police academy classes because they are not known to local members of the underworld.
  • Federal agencies may transfer suitable personnel to areas where they are not known.

Lineups

  • The traditional identification procedure used to focus a case against a suspect when eyewitnesses are available.
  • Field lineups are conducted shortly after the crime and may be done at the scene.
  • Photographic lineup usually has 4 to 6 suspects with similar appearances.
  • The lineup may be conducted as a physical lineup similar to what is seen on TV.
  • Figure references: ordinary practice includes demonstrating how lineups connect eyewitness testimony to a suspect.