Executives at Armor Holdings Inc., a military equipment company in Florida, learned in 2007 that one of their own had been paying bribes to obtain and keep business. The company reached out to the U.S. Justice Department and agreed to turn over everything from its internal investigation of Richard Bistrong.

Three years later, Bistrong has become a key player in the government’s largest prosecution of alleged Foreign Corrupt Practices Act violations. Bistrong helped the government build its case against industry executives with whom he had associated. And the 14 million pages of documents from Armor — including witness interviews, e-mail files and hard drives — is now a target for defense lawyers.