The Association of Certified Fraud Examiners (ACFE) published a report of their research that indicated "whistleblower tips are by far the most common way that fraud schemes are detected."  The ACFE conducted a survey of whistleblower programs and in this report provided guidance gleaned from their survey on how internal audit leaders and other professionals can manage and support whistleblower hotline programs. 

Read the report at this link: Building a Best-in-Class Whistleblower Hotline Program