Evidence and Exhibit Handling

Evidence and exhibit handling refers to the practices by which investigators collect, preserve, and record material gathered during a corruption investigation, in a manner that supports both the accuracy of the investigation's conclusions and the material's admissibility should the matter proceed further, including to disciplinary proceedings, civil litigation, or criminal prosecution. Sound evidence handling requires attention to the type of evidence being gathered, the maintenance of an unbroken chain of custody, the confidentiality of material and sources during the investigation, and the creation of comprehensive, properly stored written records.

1 Inculpatory and Exculpatory Evidence

A foundational principle of evidence gathering in corruption investigations is that investigators must actively seek out both evidence that tends to support an allegation (inculpatory evidence) and evidence that tends to rebut it (exculpatory evidence). An investigation that only pursues material confirming an initial theory of the case risks reaching an unsound or unfair conclusion, and can fail the evidence rule component of procedural fairness. Investigators are expected to weigh the sufficiency and quality of all evidence gathered, on both sides, before drawing conclusions, a discipline that also underpins the standard of proof ultimately applied to the findings.

2 Types of Evidence

Corruption investigations typically draw on three broad categories of evidence. Testimonial evidence consists of witness statements and interview accounts obtained from reporting persons, witnesses, and the subject of the investigation, commonly gathered using a structured approach such as the PEACE interview framework. Documentary evidence includes material such as emails, phone records, meeting minutes, contracts, bank records, audit logs, and timesheets, and is often central to establishing a timeline or verifying an account given in interview. Real evidence, sometimes called physical evidence, includes CCTV footage, photographs, and physical objects relevant to the allegations. Each category carries different considerations for collection and preservation: documentary and real evidence generally require careful attention to chain of custody, while testimonial evidence requires accurate contemporaneous recording of what was said and by whom.

3 Chain of Custody and Exhibit Continuity

Once evidence is collected, its security and continuity must be maintained from the point of collection through to its eventual disposal. This principle, commonly referred to as chain of custody or exhibit continuity, requires that at every point where an exhibit changes hands, is moved, or is examined, a record is made of who handled it, when, and why. The purpose of maintaining this unbroken record is twofold: it protects the exhibit against tampering or contamination, and it allows the investigation to rebut any later claim that the evidence was altered, substituted, or mishandled. In practice, exhibit continuity is typically maintained through a dedicated case or records management system, supported by contemporaneous notes made by investigators at the time evidence is collected or handled, rather than reconstructed after the fact from memory.

4 Legal Compliance in Collection

The collection of evidence must comply with applicable Australian laws of evidence and with the Australian Government Investigations Standards 2022, which at paragraph 3.2.4 sets out requirements governing the search for, collection of, and seizure of evidence. These requirements are designed to ensure that evidence gathered during an internal investigation is obtained lawfully and in a manner that will not later be excluded or discredited on the basis that it was improperly collected. Investigators should be familiar with any specific search, seizure, or access powers applicable to their agency, and should not assume that internal administrative status grants unlimited access to a person's records, devices, or communications without appropriate authority.

5 Confidentiality During Evidence Gathering

Evidence and information gathered during a corruption investigation should be shared only on a need-to-know basis. Unnecessary disclosure of an investigation's existence, scope, or content creates several serious risks: it can prompt destruction or alteration of evidence by a person aware they are under scrutiny; it can enable interference with witnesses, whether through pressure, coordination of accounts, or intimidation; it can taint the recollections of witnesses who become aware of other accounts before giving their own; it can undermine the willingness of witnesses and reporting persons to cooperate, particularly where they fear exposure; it can expose reporting persons and witnesses to reprisal; and it can cause unfair reputational damage to a subject who is ultimately found not to have engaged in corrupt conduct. Maintaining tight confidentiality around an active investigation is therefore not merely an administrative preference but a substantive protection for the integrity of the evidence and the fairness of the process to everyone involved, including reporting persons whose protections are discussed at Whistleblowers and Disclosers.

6 Record-Keeping Requirements

Investigators are expected to maintain comprehensive written records of the investigation, including records of evidence collected, interviews conducted, decisions made, and the reasoning behind those decisions. These investigation records should be kept separately from the personnel files of any individuals involved, including the subject of the investigation, in order to protect the confidentiality of the investigation and to avoid inappropriately embedding unproven allegations within a person's ordinary employment record. Where a cross-reference between the personnel file and the investigation record is necessary for administrative purposes, it should be limited to the minimum information needed to indicate that a separate, confidentially held record exists, rather than reproducing the substance of the investigation itself.

See also: Conducting a Corruption Investigation, PEACE Interview Framework, Whistleblowers and Disclosers.

References

1. Australian Government Investigations Standards 2022, para 3.2.4.
2. Commonwealth of Australia, National Anti-Corruption Commission, Conducting internal investigations into corrupt conduct: A guide for Commonwealth agencies (updated July 2026).
3. Public Interest Disclosure Act 2013 (Cth).