The bad news for the Zetas began on June 12, with the arrest of Jose Treviño Morales in Oklahoma. Treviño (pictured, left), the brother of Zetas boss Miguel Angel Treviño, alias "Z-40", stands accused of using drug profits to raise thoroughbreds and run a horse racing operation. His son, Juan Francisco Treviño, was arrested in a shopping center in Monterrey on June 15, accompanied by a cousin, two unrelated women, and at least two assault rifles.

Days after Jose Treviño’s arrest, Francisco Colorado, a Veracruz businessman with deep ties to the Zetas, turned himself in to the authorities in Texas, where, like Jose Treviño, he stands accused of using his links to the quarter-horse racing circuit to hide revenues from the drug trade. In recent years, Colorado’s company, ADT Petroservicios, secured contracts worth more than $100 million with Mexico’s national oil company. Authorities accuse him of using his company as a front for the Zetas, the gang that has become more deeply involved in the black market for oil than any other in Mexico.

Finally, on June 14, the Mexican Army announced the arrest of Gregorio Villanueva Salas, who was charged with overseeing a vast pirate merchandise operation, as well as perpetrating attacks on schools, media outlets, and military bases in Matamoros, Tamaulipas, earlier this year. The Zetas have been among the most aggressive of the Mexican gangs in exploiting the potential of the nation’s vast informal economy as a source of income.

The string of arrests targets those suspected of laundering the Zetas’ revenues in the legitimate economy. This push to attack the finances of one of Mexico’s foremost criminal groups responds to longstanding criticisms of President Felipe Calderon’s criminal policies, and fits with strategic shifts promised by his likely successor, opposition politician Enrique Peña Nieto. Peña recently announced that, if voted in, he would appoint Colombian police General Oscar Naranjo as security advisor, who has promised to bring to Mexico a more robust focus on the financial networks supporting the country's criminal groups, emulating a strategy implemented in Colombia.

However, despite the new focus on the issue, it’s not clear that a crackdown on money laundering will be a key step in bringing about a safer Mexico. Given the small size of the drug trade relative to total economic output, the authorities may not be capable of consistently identifying criminal revenue flows within the legitimate economy. Furthermore, as InSight Crime and others have argued, focusing on criminals’ finances may not hit the incentives for drug trafficking; indeed, a trafficker faced with reduced profit margins caused by attacks on his financial networks may well decide to ramp up the traffic of drugs or other criminal activities, in order to replace the lost income.

That’s not to say that the arrests of the past week are useless. While the importance of operations against money laundering is often exaggerated, recent arrests do indeed reflect the wide range of revenue streams feeding the Zetas’ coffers. The removal of a pirate merchandise mogul and an oil exec with extensive connections to Mexico’s oil industry could well bring about a long-term disruption of the Zetas’ cash flow, beyond what would be possible from the arrest of a money launderer alone.

The recent arrests may also contribute to a crackdown on some notorious state governments. Colorado’s business received hundreds of thousands of dollars in contracts from the administration of former Veracruz Governor Fidel Herrera, who left office in 2011 and whose term coincided with an upsurge in criminal activity, especially linked to the Zetas, in the Gulf state. While Herrera has not been directly implicated in the case, so far, one fellow former governor, Tomas Yarrington of neighboring Tamaulipas, is being investigated for links to the Zetas. Both Yarrington and Herrera are members of the Institutional Revolutionary Party, or PRI.

The spate of arrests targeting the Zetas also reflects policy objectives on both sides of the Rio Grande. The group was declared the Mexican government’s top priority last summer, thanks to a series of provocative actions, including mass killings and the murder of a US agent. The Zetas have also been named as a top target by the US government, and the detentions in Mexico following Treviño’s arrest offers a further demonstration of Mexican authorities’ willingness to buy into US priorities on organized crime