A Mexican cocaine-trafficking network used accounts at Bank of America Corp. to hide money and invest drug-derived proceeds in U.S. quarter horses, the Federal Bureau of Investigation said.

The FBI laid out the alleged ties between Los Zetas and Bank of America in a 35-page affidavit filed last month in Dallas federal court, the Wall Street Journal reported. According to Jason Preece, an FBI agent, a horse-buying and trading business allegedly used to launder Zetas drug money held accounts at the Charlotte, N.C.-based bank.

"The ultimate goal of this money laundering operation was to provide Jose Trevino with apparent legitimate assets purchased and maintained by illegally obtained money," Preece said in the affidavit.

Trevino, a U.S. citizen, is the brother of Miguel Angel Trevino Morales, the leader of Los Zetas. The two of them, along with 12 others, were indicted last month for their alleged roles in a conspiracy to launder Zetas money through the purchase, training, breeding and racing American quarter horses in the U.S.

The affidavit describes about a dozen transactions since December 2009 in which more than $1.5 million was deposited or withdrawn from two accounts at the bank. The Journal reported that Bank of America isn't accused of any wrongdoing, and citing people familiar with the case, reported that the bank is cooperating.