Federal prosecutors have been conducting a criminal investigation alongside the civil forfeiture case involving 17 bank accounts of Mexican restaurants in Wyoming and Colorado, according to court documents filed last week by Wyoming U.S. Attorney Mark Klaassen.

As a result, the Wyoming U.S. Attorney's Office on Friday asked U.S. District Court Judge Alan Johnson to stop the research in the civil case because it "will adversely affect the ability of the United States to conduct the related criminal investigation," according to the motion.

Those adverse effects of continuing the research, known as discovery, could compromise the criminal investigation and it could lead to the harm of witnesses, according to the motion.

On Friday, in conjunction with the motion to delay the civil forfeiture proceedings, federal prosecutors filed an amended complaint for forfeiture.

The case started in 2016 when federal agents identified cash-down purchases of $10,000 or more on vehicles in Cheyenne, found suspicious cash deposits related to the Mexican restaurants and an alleged wholesale food supplier in Colorado Springs. The owner of that business, Jose Aguilar-Martinez, allegedly had contact with the recently convicted drug lord known as "El Chapo," according to the complaint for forfeiture.

One of the restaurants named in the civil forfeiture case is Rodolfo's Mexican Grill in Cheyenne. Its owner, Hilario Montejano-Aleman, says his bank accounts have not been used in drug money laundering.

In June, the U.S. Drug Enforcement Administration seized U.S. currency and bank accounts and two safe deposit boxes because it was determined to be either illegal drug proceeds or in accounts used to launder illegal drug proceeds with other money.

In November, the federal prosecutors requested the forfeiture of about $1.5 million in cash seized from 17 bank accounts and safe deposit boxes, which are the defendants in the case.

In the following months, many of those controlling the accounts and boxes filed claims for the money, filed answers to the forfeiture request, and some asked Johnson to dismiss the case.

Johnson has denied all the motions to dismiss.

The federal prosecutors wrote that continuing the civil forfeiture case would require them to reveal names, addresses and phone numbers of witnesses with information, according to the motion.

Revealing that information also could compromise witnesses' safety, according to the motion. "[That] will necessarily adversely impact the investigator's ability to protect potential witnesses in the criminal investigation from improper influence or contact from claimants and their supporters."

The potential criminal defendants also could "use the broad net of civil discovery" to learn everything the federal prosecutors know and that would subvert the parallel civil and criminal proceedings, and affect the integrity of trial evidence, according to the motion.