A corruption probe is a criminal or civil investigation into alleged bribery, embezzlement or other forms of corrupt behaviour. It may be conducted internally by an organisation through its own disciplinary processes or by outside investigators. It is essential that all cases of corruption are properly investigated so as to prevent further misuse of public funds. Grand corruption is rarely proved by a single piece of evidence, so investigations must be conducted like a jigsaw and put together carefully.

Often, the first indication of possible corruption is a whistleblower or a leak. It is important to evaluate the credibility and motivation of the source and to corroborate it. Then the investigator must decide how to investigate the allegations, for example by interviewing the primary subject (and potentially seeking helpful admissions) and examining third party records such as those of suspect contractors, through the exercise of contract audit rights or through obtaining subpoenas and search warrants.

It is also important to examine whether a company or public body has any policies that would make it difficult for it to engage in corruption. This should be compared to its anti-corruption legislation and to its record of compliance with those laws. It is often useful to consult with legal specialists who can help coordinate all aspects of what is likely to be a complex case and to work with external investigating authorities. This is particularly important if the corruption involves cross-border elements.