The Farmington Police Gang Unit said the shooting was gang-related and caused increased tension among two rival gangs.
"Gangs are unpredictable. They could never retaliate, they could retaliate the next day," said Farmington police Cpl. David Karst, the gang unit supervisor. "There are different ways of retaliation; drive-by shootings, personal killings, assassinations. They are so unpredictable it's hard to tell."
Brothers Alejandro Ramirez, 22, and Luis Ramirez, 28, have been arrested on suspicion of killing Johnny Benjamin Vialpando, 25. Vialpando was shot and killed on April 27, while he was a passenger in a car parked at the mall. His wife and children and several other people witnessed the shooting.
The Ramirez brothers are local gang members, Karst said.
A suspect matching Alejandro Ramirez's description approached Vialpando and said, "This is for Gary," just before shooting him 15 times, according to court documents.
Police believe that was a reference to Gary Martinez, a 17-year-old who was killed in what police believe was a gang-related drive-by shooting in October 2008. After the shooting, police questioned Vialpando, but he was never charged with a crime in connection to Martinez's death. The case remains unsolved.
Police declined to discuss the specific gang affiliations of the people involved in the shooting. But they said the shooting involved people linked to Farmington's two largest gangs: the South Side Locos and Tortilla Flats.
"The recent South Side-Tortilla Flats incident ... has caused a lot of conversations and tension between the two gangs," said Erik Haanes, an officer in the gang unit.
According to police, more than 600 gang members live in San Juan County, and there are about eight confirmed gangs in the region.
Gangs include people of all ethnicities, Karst said.
The South Side Locos are the largest gang in the area and are comprised of many sects. The next largest gang is Tortilla Flats, according to the gang unit.
Both gangs have a strong presence in south Farmington. But unlike gangs in certain cities that have strict boundaries separated by something as obvious as a street, Farmington's gangs scatter throughout the area and collaborate with members of opposing gangs to commit crimes, Karst said.
The gangs commit crimes often to make money and intimidate rivals. In Farmington, the two most common crimes gangs commit are dealing drugs and guns, Karst said. But they also rob, burglarize and steal identities.
"They do criminal activity to further the gang. It's not just a group of criminals banding together to burglarize a house for their own gain," he said. "Whatever they are doing is an enterprise for a group."
Throughout the country, there are gangs that call themselves South Side Locos and Tortilla Flats, but local neighborhood gang groups take on the attributes of their leaders, said Moises Prospero, an adjunct professor of criminology at New Mexico State University.
"Your loyalty comes from your neighborhood," he said. "They may have a sense of belonging, but they are not soldiers."
In addition to committing crimes for financial benefit, gangs also seek to intimidate rivals and gain respect from members of their own gang.
"An alleged homicide is the ultimate form of disrespect," Karst said.
If a gang thinks a rival gang has disrespected it maybe through a gang-related shooting or a drug deal gone bad gang members can opt to retaliate to regain respect.
And retaliation can be deadly, putting both the target and passersby at risk.
"Respect is huge in all this," Prospero said. "If you have respect, that's a huge benefit. If you live in a violent, poor, tough neighborhood and you are respected by a gang, you are safe."
At NMSU, Prospero is researching types of strategies that could reduce gun violence.
He said one successful approach involves hitting gang violence from multiple directions. On the police side, an effective strategy requires visible patrol, a police crackdown on problem areas and undercover work by gang units to gather intelligence before a crime.
"True, hardcore gang members are sociopaths, and they need to be in prison," Prospero said.
But long-term change needs to involve having social services follow the police and offer drug treatment, education and jobs to people in gang-riddled neighborhoods, he said.
Karst said the police's success at cracking down on gangs requires the public's help.
"The more they see, the more they report, the more they cooperate, the more effective we are at being able to take these people out of our community," Karst said. "The more help we get from them, the more successful we are going to be."
Ryan Boetel can be reached at email@example.com; 505-564-4644. Follow him on Twitter @rboetel.