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Investigator Tip: Conducting the Investigation

When a crime has been committed, there are several general guidelines that should be followed in conducting a thorough investigation.

Developing the Case Facts

“Fact analysis” refers to the investigator’s ability to identify from factual information the probable motivation for a crime, unique access requirements (for example, access to a particular type of weapon or vehicle, knowledge of a security code or possession of keys), the window of time during which the crime was committed (to establish opportunity), and propensity characteristics about the person who committed the crime (for example highly intelligent, emotional or a drug user, etc.).

The following are suggestions with respect to collecting and analyzing factual information:

• Prior to an interview, and preferably before any contact with the suspect, the investigator should attempt to become thoroughly familiar with all the known facts and circumstances of the offense.
• In cases involving a victim, such as a robbery or assault, the victim should be the first person interviewed, as well any witnesses.
• The investigator should interview those suspects who are least likely to be guilty first and work toward the suspect most likely involved in the offense.
• Remember that when circumstantial evidence or especially physical evidence points toward a particular person, that person is usually the one who committed the offense.
• After obtaining information from the person providing the details re the commission of the crime (e.g., the investigating officer), consider the possibility that the fact-giver may have become so convinced of the suspect’s guilt and so anxious to obtain a confession himself that he prematurely may have confronted the suspect with an accusation or may have indulged in some verbal abuse.
• Consider that a fact-giver may have worked so many hours or days on a case that, without any malicious intent, he may have withheld relevant information or even have supplied unfounded information to the investigator.
• While listening to a fact-giver’s report of the incident in question, jot down notes regarding dates, time, and nicknames of participants or witnesses, and fill in the complete details later rather than interrupt the fact-giver who is presenting the report.
• In appropriate situations, encourage the person relating the details of a case to sketch the place of occurrence and to note on it any relevant points.
• When interviewing a person regarding the facts of a case, ask what he believes may have happened, who he believes to be the chief suspect, and why
• Regard cautiously the reliability of information submitted by a paid informer.
• View with suspicion any anonymous report implicating a specific person in a criminal offense.
• Ask a child victim of a sexual offense involving a stranger to describe the scene of the offense.
• During an interview with the presumed victim or other reporter of a crime that involves money or property rather than a physical offense, consider the possibility that no crime was in fact committed.