For your information, the cartels that are openly operating in Panama include:
(1) Los Zetas
(2) The Juárez Cartel
(3) The Gulf Cartel
(4) The Beltran Leyva Cartel
If Mexican "businessmen," seeking to invest their capital through your bank, and commence a new account relationship, are using Panama corporations as their vehicle, beware. Panama's bearer shares cannot be definitively tied to your new clients, as beneficial owners, and you may be doing business with the Devil, or at least his Mexican counterparts, any individuals on the OFAC list.
if still wish to take their business, choose a reputable investigative firm in Panama, not staffed with local (and therefore corruptable) talent, and have it check them out, in both Panama & in Mexico. If their "employment," or business they claim to own and operate is a fiction, exit them immediately. If the Source of their wealth cannot be ascertained, close their accounts. finally, watch for front men, all with good references, who are markedly unfamiliar with legalese, and the jargon of finance.