The arrests come after the brutal killings south of the Arizona border in Sonora state, which attracted international attention to otherwise isolated fundamentalist communities that live along the border.
According to a statement from the federal prosecutor’s office, the arrests followed work done by judicial and intelligence officials, as well as soldiers and national guard troops.
A raid was reportedly carried out on Sunday, but the location was not disclosed publicly. The arrests come after the detention and arraignment of a suspect in November, who provided “fundamental information and evidence” related to the case, according to USA Today.
But, family members told the newspaper they were sceptical about the news of the arrests.
“I would imagine these are low-level people,” said Julian LeBaron, a family spokesperson and relative. “We want to know who gave the order and who is responsible.”
Mr LeBaron had previously said that the family was not convinced that all of the evidence possible had been accounted for in the case.
“There’s a video that the FBI has of 12 guys dressed in black with helmets, like special forces, coming down the hill, opening fire on my cousin’s vehicle,” he told USA Today previously. “When they got to the vehicle, they got her purse … I don’t think anyone questions the fact that it was targeted.”
The violence south of the US-Mexico border has left more than 30,000 Mexicans dead in the past year, and the unrest shows little signs of abating.
The 4 November attack left six children dead alongside three adult women.
In response, some family members urged Donald Trump to designate the Mexican cartels as terrorist organisations — a move the president said recently he would “absolutely” do.
But Mexican authorities, including president Andres Manuel Lopez Obrador, say that the designation would amount to an unnecessary intrusion on Mexican sovereignty.
“We recognise … President Trump has offered us help and respect. That’s to say, he was respectful and offered help and at the same time respected our sovereign right to decide with independence,” Mr Lopez Obrador said on Sunday. “The government of Mexico will fulfil its responsibility to do justice.”
The LeBarons are an extended family of fundamentalist Mormons with dual US-Mexican citizenship, who have lived in northern Mexico for generations.
Additional reporting by the Associated Press