One of Mexico's most-wanted drug lords, Miguel Angel Treviño Morales, also known as "Z-40," has been captured, Mexican authorities said Monday evening.

Treviño Morales, leader of the brutal Los Zetas cartel, was caught Sunday by Mexico Marines in his hometown of Nuevo Laredo, on the U.S. border, the state-run news agency Notimex reported.

His arrest is the most significant blow to drug trafficking in Mexico since President Enrique Peña Nieto took office in December.

The U.S. State Department had offered a $5 million reward for  Treviño Morales.

The Zetas cartel is among Mexico's most violent drug organizations, notorious for civilian killings and beheadings. Its leaders ordered the killing of 72 migrants in 2010 in what is known as the San Fernando massacre. More recently in May, the Mexican army said their leaders ordered underlings to leave 49 mutilated bodies in a northern Mexico town square, CBS reports.

Treviño Morales' brother, Jose, was recently sentenced to 20 years in prison in Texas for using a racetrack to hide illegal drug profits for his brothers.

A picture obtained by The Dallas Morning News shows a beaten and bruised, and somewhat overweight, Treviño Morales hours after his detention, one official said.

The arrest of Treviño Morales is expected to unleash a new wave of violence across regions of northeastern Mexico, a U.S. law enforcement official familiar with the situation along the border told the Dallas Morning News. In the days to come, rival cartels and corrupt police authorities will try to muscle in and fill the void left by his arrest.

Treviño Morales’ younger brother, Omar, who was also raised partly in Dallas, is likely to be the new leader of the Zetas, a deadly army that has been weakened in recent months. Omar Treviño Morales, known as “42,” is known as the Zetas leader in the Piedras Negras area, across from the Texas border town of Eagle Pass.