Banking giant Wachovia Corp. will pay $160 million to settle a federal investigation into laundering of illegal drug profits through Mexican exchange houses in the largest case of its kind ever brought against a U.S. bank, prosecutors said Wednesday. "This is historic," acting U.S. Attorney Jeffrey Sloman said. "There is no other case like this one anywhere." The probe, which began in 2005 when a Drug Enforcement Administration narcotics dog in Florida detected cocaine traces in an airplane, ultimately uncovered at least $110 million in drug profits laundered from Mexico through Wachovia. The total settlement includes forfeiture in that amount plus a $50 million fine. "DEA will follow drug money wherever it leads us," said Mark R. Trouville, chief of the DEA's Miami office. The agreement means Wachovia and its executives will avoid criminal prosecution in return for the $160 million payment and significant improvements in its anti-money laundering program.