Martin is a fraud examiner. He contacts Dianne for the purpose of conducting a routine, information- gathering interview. Dianne says that she wants her coworker. Sheila, whom Martin also plans to interview, to be present during the interview. Martin should:

The standard and best practice for conducting interviews is to speak with one person at a time. Interviewing Dianne and Sheila separately prevents them from influencing each other's statements, either intentionally or unintentionally. This ensures that the fraud examiner obtains independent recollections from each witness, which is critical for the integrity of the investigation. The presence of another witness can lead to contaminated testimony, making it difficult to ascertain the truth. Martin should politely explain the need for individual interviews and proceed with them separately.

B. Sheila's mere presence, even if silent, can influence Dianne's answers through non-verbal cues or intimidation, contaminating the interview.
C. Interviewing witnesses together is strongly discouraged as it allows them to conform their stories and makes controlling the interview difficult.
D. While having a second interviewer is good practice, it does not solve the fundamental problem of witness contamination created by a joint interview.

ACFE. (2023). Fraud Examiners Manual, International Edition. Section 4, "Interviewing Witnesses," Subsection "Planning and Conducting Interviews," Chapter "General Rules for an Interview." The manual explicitly states, "As a rule, interview only one person at a time... If two people are interviewed at the same time, they will be inclined to feed off each other’s answers."