State investigators arrested William Alfonso Fonseca Reyes, 29, alias "El Chicano," during the weekend in connection with the deaths of lawyers Salvador Urbina Quiroz and Cesar Cordero Gutierrez.
The lawyers were shot to death on May 26 inside Urbina's law office in Juárez.
Prosecutors alleged Fonseca leads a crew of the Artistas Asesinos, a gang known as the Double A that is allied with the Sinaloa drug cartel.
The state attorney general's office released photos of Fonseca shirtless with several tattoos, including an "A" on the front of each shoulder.
A Facebook page in Fonseca's name has photos of him holding guns as well as family photos.
In 2008, Fonseca was among seven inmates who were transferred in a Mexican army operation from the Juárez Cereso prison to the state prison because they were allegedly planning a riot, according to Mexican news archives.
The Norte newspaper reported Urbina was targeted because of his defense work in an unspecified federal case.
Fonseca, who is originally from the Mexico City area, said he was simply a baker and not involved in criminal activity, according to the Norte.
Urbina, 52, was a former president of the Juárez Lawyers' Association, a former deputy director of the Cereso prison in Juárez and had several high-profile cases.
Shortly after the killings, authorities released a security camera video showing two suspected killers at Urbina's office.
The video shows the men standing in the doorway before one of them takes out a handgun and enters while the second man continues to stand by the door.
On May 29, state police arrested one of the suspected shooter, Oscar Adrian Martinez Martinez, 25, aka "El Batres."
"Following the arrest of 'El Batres' valuable information was obtained, a motive was established and the mastermind behind the double homicide was identified," the attorney general's office said in a news release.
The second man involved in the shooting has not been arrested.
Source: El Paso Time posted by siskiyou_kid