Since the 1990s, when whistleblowers became an integral part in the fight against health care fraud, they have helped the federal government recover $9.3 billion from health care-related parties who have fraudulently billed the government, according to a study published in the Annals of Internal Medicine. Whistleblowers are the source of 90 percent of the health care fraud cases that the DOJ investigates. In a whistleblower case, the documents filed with the court are placed under seal. The DOJ reviews the sealed documents to determine whether it wants to intervene in the case. If the DOJ decides to intervene, the whistleblower usually receives between 15 and 25 percent of the amount recovered by the DOJ. Whistleblowers have received more than $1 billion of the $9.3 billion that was recovered from 1995 to 2005.