Assistant U.S. Attorney Richard Elias was leafing through a pile of JPMorgan Chase & Co. documents in 2012 when he found a memo in which one JPMorgan employee warned her bosses they were putting bad loans into securities being created before the financial crisis hit, according to a Wall Street Journal analysis today. The U.S. attorney’s office in Sacramento, Calif., soon started sending subpoenas to JPMorgan officials tied to the memo. Three months later, top Justice Department officials in Washington, D.C., told investigative teams across the country to hunt for similar ammunition in tens of millions of documents from other banks, especially Bank of America Corp. and Citigroup Inc. Elias’s discovery has delivered a whopping payoff so far: $36.65 billion, representing the cost of the government’s three separate settlements with the banks since late 2013, including the $16.65 billion deal with Bank of America in August that is the largest ever between the U.S. and a single company.