(CNN) -- American-born Edgar Valdez Villarreal, believed to be one of Mexico's most ruthless drug traffickers, was captured Monday, Mexican authorities said.

Federal police made the capture, though the exact location and timing of it were not immediately known.

The arrest, a high-profile win for Mexican authorities, followed "intelligence work" that began in June 2009, federal police said in a statement.

His capture came after a shootout, according to Viviana Macias, a spokeswoman with the federal attorney general's office.

Valdez, who is known as "La Barbie" because of his blue eyes and fair complexion, was a one-time top lieutenant of Mexico's most wanted man, Joaquin "El Chapo" Guzman.

Valdez later joined the breakaway Beltran Leyva cartel, but the leader of that group, Arturo Beltran Leyva, was killed in a shootout with Mexican officials late last year. Beltran's brother Carlos was arrested, leaving Valdez in a fight to fill a power vacuum in one of Mexico's most powerful drug cartels.

Lieutenants loyal to the cartel's co-founder deny Valdez is the group's leader, federal police have said.

Valdez, thought to be the first U.S.-born cartel leader in Mexico, is accused in the United States of attempting to launder money and conspiring to import and distribute cocaine. He is believed to have played a key role in shipping roughly 100 kilograms of cocaine across the border at Laredo, Texas, every week for much of 2005, U.S. authorities have said.

U.S. Justice Department officials offered in June a $2 million reward for information leading to the capture of the alleged cocaine kingpin.

His arrest comes on the heels of another big blow against the drug cartels. Ignacio "Nacho" Coronel Villareal, a principle leader of the Sinaloa drug cartel, was killed during a military raid in July.

More than 28,000 people have died in drug-related violence since Mexican President Felipe Calderon intensified the government's fight against drug cartels and organized crime after taking office in December 2006, according to government figures. The president is under increasing pressure to show results.