A US appeals court has overturned a conviction and ordered a retrial for US citizens accused of laundering drug profits for Mexico’s Zetas through racehorses, in a case that illustrates the challenges in breaking down transnational money laundering networks.

A three-judge panel at a Federal Appeals Court in New Orleans has overturned the money laundering conviction of horse trainer Eusevio Maldonado Huitron, stating that prosecutors failed to demonstrate his intentional involvement in illegal activities.

While the judges did not dispute that the horse stables where Maldonado worked were used to launder money for Mexico’s Zetas cartel, they argued that there was no evidence to indicate Maldonado had taken part in anything but training the horses bought with drug money.

The ruling also called for a retrial in the case of Francisco Colorado Cessa, who prosecutors alleged had founded a company with a loan from a Zetas member and purchased horses on behalf of the cartel with illicit funds.

The judges made the decision based on the instructions given to the jury by the trial judge, who told them they must consider the defendant guilty of money laundering if they believed there was a commingling of legal money from his business with illegal funds. However, the new ruling states, this is incorrect, and the jury should have been instructed that although they could come to that conclusion, they could also decide otherwise — that the mixing of legal and illegal revenues was not a deliberate attempt to launder money.

The convictions of the two other men involved in the trial, Fernando Garcia Solis and Jose Treviño Morales, the brother of Zetas leaders Z40 and Z42, were upheld.

InSight Crime Analysis

The story of how the Zetas infiltrated the world of US horse racing to launder their drug trade profits has become one of the most infamous cases exposing the US business interests of Mexican cartels.

However, with this latest ruling, it is now also an example of just how difficult it is to prosecute money laundering cases. Even after prosecutors had firmly established that the business was used to disguise criminal profits, proving that all of the front men involved were aware of its illegal purpose has proved much more complicated.

SEE ALSO: Zetas News and Profile

Tackling organized crime by going after its financial assets can be one of the most effective ways of targeting networks, as it hits crime bosses where it hurts them most — in their pockets. However, unpicking criminal business interests from legal ones is a long, complicated process that, as in this case, can be derailed by uncertainties.