Federal and state authorities are investigating [several] major American banks for failing to monitor cash transactions in and out of their branches, a lapse that may have enabled drug dealers and terrorists to launder tainted money. Regulators, led by the Office of the Comptroller of the Currency, are close to taking action against JPMorgan Chase for insufficient safeguards. The agency is also scrutinizing several other Wall Street giants, including Bank of America. In addition to the comptroller, prosecutors from the Justice Department and the Manhattan district attorney's office are investigating several financial institutions in the United States. The surge in investigations, compliance experts say, is coming now because authorities were previously inundated with problems stemming from the 2008 financial turmoil. Until now, investigators have primarily focused on financial transactions at European banks. The authorities accused several foreign banks of flouting American law by transferring billions of dollars on behalf of sanctioned nations. As the investigation shifts to American shores, the Justice Department and the Manhattan district attorney's office are moving beyond those violations to focus on money-laundering, in which criminals around the globe try to hide illicit funds in United States bank accounts.