(CNN) -- Mexican authorities said Monday that they had arrested a Zetas drug cartel leader who was connected with the killing of a U.S. Immigration and Customs Enforcement agent this year.
Federal police captured Jesus Enrique Rejon Aguilar, known as "El Mamito," Sunday, a top official with the agency said.
Rejon is suspected of being behind numerous deaths in northeastern Mexico, where the Zetas have been engaged in a turf battle with their former allies, the Gulf Cartel.
Rejon was a former member of the Mexican Army's elite forces who deserted in February 1999, according to Ramon E. Pequeno, anti-drug division chief of Mexico's federal police. The following month, he joined the group that founded the Zetas, Pequeno said.
He is also "connected to the attack against agents" of U.S. Immigration and Customs Enforcement that killed Agent Jaime Zapata in February, a statement from Mexico's public safety secretary said.
Pequeno said Rejon was in charge of operations for the Zetas in the north central Mexican state of San Luis Potosi when the American agents were ambushed there.
"When [U.S. agent] Jaime Zapata was murdered on February 14, El Mamito was in San Luis Potosi, coordinating actions perpetrated by the Zetas," Pequeno said.
Zapata was killed and another agent injured when they were ambushed on a highway in San Luis Potosi as they traveled from Monterrey to Mexico City.The U.S. Drug Enforcement Administration had offered a $5 million reward for information leading to Rejon's arrest.
The two were traveling to Mexico City in an armored car with diplomatic plates. They were run off the road and attacked from two vehicles by gunmen who opened fire indiscriminately. It was the first time in 25 years that a U.S. law enforcement agent was killed while on duty in Mexico.
The incident prompted swift action by Mexican authorities and just eight days after the shooting, they announced the arrest of the presumed leader of a group of killers allegedly involved in Zapata's killing, which was apparently carried out by mistake.
Mexican authorities called Rejon "one of the leaders and founders of the Zetas criminal organization."
They said he was the third most powerful leader of the drug cartel, which was created by deserters of the Mexican Army's elite forces.
Rejon is also being investigated for the deaths of dozens of Central and South American migrants whose bodies where found in the northern Mexican state of Tamaulipas at a ranch just 100 miles south of the U.S. border.
Pequeno called Rejon's arrest "a triumph for the Mexican government."
"El Mamito's capture is emblematic because he was one of the original Zetas," he added.
CNN's Catherine E. Shoichet contributed to this report.