- Mexico's navy says it has arrested Jorge Eduardo Costilla Sanchez
- He is said to be the leader of the Gulf cartel
- More details will be released Thursday
- Multimillion-dollar rewards were offered for his capture in Mexico and the United States
(CNN) -- Mexico's navy on Thursday will provide details about the arrest of a man they say is the top leader of one of Mexico's major drug trafficking organizations, the Gulf cartel.
If verified, it would be a much needed achievement for outgoing President Felipe Calderon, whose offensive against drug cartels has done little to stem drug-related violence or the volume of drugs transported through Mexico.
The navy said that a person "presumed to be and who says he is" Jorge Eduardo Costilla Sanchez was arrested in the border state of Tamaulipas on Wednesday.
There are multimillion-dollar rewards in Mexico and the United States for the arrest of Costilla, also known as "El Coss."
Costilla has been indicted in the United States, accused of drug trafficking and threatening U.S. law enforcement officials in November 1999.
In that incident, according to the U.S. State Department, Costilla and other Gulf cartel leaders stopped FBI and DEA agents and pointed AK-47 rifles at them. The agents were allowed to leave after a standoff.
The State Department offered a reward of up to $5 million for information leading to Costilla's arrest. In Mexico, where Costilla is on the government's list of the 37 most wanted traffickers, officials offered 30 million pesos, or about $2.3 million, for his capture.
While not as powerful as it once was, the Gulf cartel is one of Mexico's major drug trafficking organizations. Costilla assumed a top role after the arrest of former Gulf cartel boss Osiel Cardenas Guillen, and became the top leader after a rift with Cardenas' relatives in the organization.
As Costilla rose in the cartel hierarchy, the group controlled smuggling routes in northeastern Mexico by using its enforcement arm, known as Los Zetas. But the Zetas later split into its own violent cartel, and for several years has been fighting the Gulf cartel for the lucrative turf.
The arrest is the latest in a series of blows against the Gulf cartel.
This month, Mario Cardenas Guillen, leader of the Gulf faction loyal to the Cardenas family, was also arrested by the military.
The Gulf cartel is based in the city of Matamoros, across the border from Brownsville, Texas.
