An investigation cannot be properly conducted if the investigator is denied access to witnesses, suspects and relevant documents. Investigators need to ensure that they investigate with integrity, that the rights of individuals are protected, and that evidence collected is untainted and admissible in a court of law.

Most systems use one or more of the following mechanisms to ensure integrity in the investigative process:

Standard Operating Procedures

Enforcement agencies usually follow standard procedures in conducting investigations. Developing good procedures that are followed by investigators helps ensure that integrity mechanisms are in place for each stage of the process. Standard procedures also reduce the danger that investigators will make arbitrary or discriminatory decisions, which can give rise to integrity problems.

Accurate Written Reports

Accurate files and reports are essential for integrity. A written file is generally kept for each complaint, with all the information and documents collected. To handle a case, other players in the enforcement system (e.g. prosecutors) rely on the written report describing the evidence collected and the analysis performed by the investigative agency.

A comprehensive written report specifies the alleged offence, the name of the offender and other information gathered during the investigation. The report may also include: an outline of the objectives of any investigation; the scope and focus of the various phases of the investigation; the names of individuals interviewed; the information and evidence obtained, and their sources; and any follow-up measure that might be considered in the decision on how to deal with the alleged offence. It can be very difficult for a prosecutor or other enforcement official to prove a case if the information collected during the investigation is incomplete or inaccurately reported.

Appropriate Interviews

The purpose of interviewing witnesses or suspects is to obtain information and evidence. However, the information is admissible in a court of law only if investigators have complied with the procedural requirements that protect evidence and the rights of individuals. Successful interviews are usually prepared in advance. The tone of the interview is professional, and the focus is on the matter at issue. A good interview may solidify that the case is prosecuted and results in a conviction.

To avoid misunderstandings and ensure that interviewees know why they are being questioned and who is questioning them, investigators usually show proof of identity and explain the reasons for asking questions. Most systems require the consent of the person to be interviewed, unless he or she is a suspect. Investigators are particularly advised to avoid conduct that could be perceived as threatening or as offering favours in exchange for cooperation.

Investigators must carefully assess the impartiality and credibility of individuals who may have a bias. They should determine the basis of any bias and counter it through closer questioning as required. Whenever possible, investigators should obtain corroboration of information from independent sources.

Before questioning, most systems require suspects to be read their rights so that their statement will be admissible in court. Suspects usually have the right to be represented by an attorney during an interview.  This right is very strongly supported as necessary to fulfill the obligations of a State under the ICCRP with respect to adjudicatory proceedings.[1]

Sworn Statements

It is useful to make sure that critical witnesses are questioned under oath and sign their statement before a complaint or charges based on their testimony are filed. A signed statement protects against any misinterpretation of testimony. It also provides protection should witnesses change their testimony in court. In most trials a sworn statement can be submitted as evidence.  It is a violation of professional norms for investigators to pressure complainants/witnesses into signing a statement, or unduly prolonging their interrogation for this purpose.

Accurate Interview Notes

It is essential to record in writing the information obtained during an investigatory interview, especially if a signed statement is not made. The notes from the investigation may be used as evidence for what a person said. In court, the defence counsel usually has a right to examine the investigator's notes, at least if the investigator refers to them when testifying.

The integrity of the interview also depends on the accuracy of the notes. Most investigators try to take word-for-word notes of an interview. In some cases, the interview may be recorded electronically. A recording is much more accurate than handwritten notes but can raise concerns. Some systems do not allow taping without prior permission or a warrant.