Assessing Credibility in a Workplace Investigation

Use these investigation guidelines to figure out who's telling the truth.

In some workplace investigations, the facts are clear. Sometimes, everyone agrees about what happened, but not about whether it was appropriate. In a harassment investigation, for example, both employees might agree the one asked the other out on a date several times. But the asker might believe this was harmless flirtation, while the askee found it to be unwanted and hostile. Here, the investigator doesn’t have to decide the facts, but instead must decide what to do about what everyone agrees happened.

In many investigations, however, the facts are less clear. Often, the main witnesses contradict each other, in the classic “he said, she said” scenario.

Now you’re facing what may be the hardest part of your job as investigator: reaching a conclusion about what happened. You have interviewed all the witnesses. You have gathered relevant evidence. But how do you decide who is telling the truth and who is lying? How do you figure out what actually occurred and why?

Because every investigation—and every person involved in an investigation—is a little bit different, there’s no single formula to apply or test to use that will always lead you to the right answers. When you’re faced with conflicting stories—as happens in many investigations—you will have to consider each person’s version of the facts. Evaluating credibility and determining who’s telling the truth can be difficult, but the following guidelines will help you sift through the evidence:


Whose story makes the most sense? Does one person’s version of events defy logic or common sense? Based on your visit to the scene, could the employees involved have heard and seen what they claimed to have witnessed? Should they have heard and seen things that they did not admit?

Source of information

Did the witness see or hear the event directly? Did the witness report firsthand knowledge or rely on secondhand statements from other employees or rumors?


How general or specific was each person’s statement? If a witness gave a detailed statement, were those details supported by other evidence? Did the accused or suspected employee deny the allegations in detail or only generally?

Corroboration and Conflicting Testimony

Are there witnesses or documents that support one side of the story? Does the evidence contradict one person’s statements? Do the witnesses support the person who suggested you interview them? If there are conflicts, are they over minor or significant issues?


Was each person’s story consistent throughout your questioning or on a second telling? Did any of the witnesses contradict themselves during your interview? If so, did the change involve a minor issue or a matter of substance?


How did the witnesses act during the interview? Did the accused employee have a strong reaction to the complaint or no reaction at all? Did the complaining employee seem genuinely upset? Were any witnesses’ reactions unusual, based on their typical demeanor or behavior? Judging demeanor can be tough—even for the experts—and you certainly shouldn’t base your conclusions on demeanor alone. But you should consider any reactions that are particularly strong or unexpected.


Did anyone leave out important information during the interview? Is there a sensible explanation for the omission? Did an accused or suspected employee admit an important detail only after being confronted with it?

Prior Incidents

Does the accused employee have a documented history of this type of misconduct? Has the complaining employee made previous complaints? Have there been other incidents between the complaining and the accused employee?


Does either the complaining worker or the accused worker have a motive to lie about, exaggerate, or deny the incident? Is there any history between these employees that affects their credibility? Do any of the witnesses have a special loyalty to—or grudge against—any of the employees involved?

For detailed information on how to interview witnesses, gather information, and investigate common workplace problems and complaints, such as harassment, theft, and drug use, get a copy of The Essential Guide to Workplace Investigations, by Lisa Guerin (Nolo).

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