Jose Antonio Acosta Hernandez, 33, is also suspected of planning the March 2010 killings of a U.S. consulate worker and her husband.
(More from GlobalPost in Mexico: Decoding Mexico’s murder mayhem)
Mexican police say that Acosta Hernandez, also known as El Diego, is the leader of the La Linea gang, whose members work as hired killers for the notoriously violent Juarez cartel, which controls the main drug smuggling routes from Mexico into the United States.
According to police, he admitted to having masterminded scores of targeted killings in northern Chihuahua state, the BBC reports.
The Mexican government had offered 15 million pesos ($1,275,000) for information leading to Acosta Hernandez's arrest.
Mexican authorities say they worked with the U.S. Drug Enforcement Agency to capture him, CNN reports.
U.S. prosecutors have said they want to try him in the case of the horrific 2010 killing of U.S. consulate employee Lesley Enriquez, her husband Arthur Redelfs, and the husband of another consular worker, Jorge Alberto Salcedo.
They were gunned down in their SUV after leaving a birthday party in Juarez, which shares a border with El Paso, Texas.
Enriquez, 35, was four months pregnant when she was killed. The couple's baby daughter survived the attack and was found crying in the back seat, the BBC says.
Mexican President Felipe Calderon, on his Twitter account, called Acosta Hernandez's arrest on Saturday “the biggest blow” to the Juarez drug cartels since he sent thousands of police officers to Ciudad Juárez last year after a spree of high-profile killings there, The New York Times reports.