A Mexican cartel apparently used a small southwest Kansas bank to launder some $2 million in drug proceeds, the U.S. Drug Enforcement Administration alleges in an affidavit.

According to The Associated Press, the agency said it investigated a couple who made 32 deposits at Plains State Bank in Plains, Kansas, starting in early 2011. Officials believe the two work for the Juarez Cartel, and on three separate occasions, U.S. Customs and Border Protection seized bulk currency from them totaling $850,000 when they entered the United States from Mexico.

After the third incident, when border agents confiscated about $170,000 in May 2014, the deposits at the bank ended, according to the DEA affidavit.

The document also supports a search warrant that was executed against a former Plains State Bank official.

Lindsey Schartz, the institution's senior vice president, said two employees involved no longer work there. She referred further comment to the U.S. attorney's office.

"It is an ongoing investigation -- that is all we can say," U.S. Attorney Barry Grissom said of the case, which was sealed after the executed warrant had been filed on Tuesday.

The cartel's suspected use of a small-town U.S. bank appears to be tied to Mexican banking regulations, which limit the amount of foreign currency that can be deposited into local accounts. In order to launder drug proceeds, the Juarez Cartel -- also known as the Mexican Mennonites -- apparently had to turn to financial institutions in the United States.

The cartel's bank of choice sits in a rural hamlet of fewer than 1,150 inhabitants. Plains forms part of a southwest Kansas region where meatpacking plants have drawn large immigrant populations.

Suspected cartel funds were deposited into U.S. accounts, and the money was then wired back to Mexico or used to buy items that were sent to that country, the DEA detailed.

The bank official who handled the couple's accounts allegedly kept records on yellow legal pads, which have since disappeared, the DEA noted. The agency claimed that the employee admitted to have processed large amounts of U.S. currency without the required information and documentation. However, no charges have been filed.