The Mormon family patriarch who lost a daughter and four grandchildren in last year’s massacre in Mexico has hailed the arrest of a feared local cartel boss — who he believes was the “mastermind” behind the slaughter.

“One more step towards knowing the truth about those who killed my children,” Adrian LeBaron, 60, wrote on Twitter Tuesday while sharing news of La Línea leader Roberto González Montes’ arrest.

LeBaron had been one of the first to stumble on the bloodbath where nine were killed and six others injured as 17 Mormons were ambushed in the Sierra Madre mountains last November.

His daughter Rhonita Miller,30, was among the dead, killed alongside four of her children, including 8-month-old twins, Titus and Tiana. All the dead were dual US-Mexico citizens.

In a statement, LeBaron praised authorities — including allies in the US — for arresting the cartel boss known as “El32” or “El Mudo,” who he called “one of the most dangerous in the region.”

“Those of us who live in the area know the serious risk involved, so their work has not been easy,” he said of the multi-agency operation that led to his arrest.

“I know that he was not the one who pulled the trigger,” he told MVS Noticias, calling him”El 32″ the “mastermind” — and saying he wanted to come face-to-face with him when he appeared in court.

He told the outlet that his family felt consolation that those involved in the slaughter “are not going to continue killing, kidnapping and making people disappear. It is something that hurts us a lot.”

Another relative, Julian LeBaron, told The Guardian that dozens more could be arrested for the massacre that was part of a turf war between rival gangs.

“Officially, we’ve been told that two cartels were duking it out and my cousins just happened to be driving by,” he told the UK paper.

“They told us that over 100 people participated in that massacre and they’re going after all of them.

“But one thing is to capture all these people, and another thing that is very distinct and different is for them to be tried, and have them go to prison for a long time. That almost never happens,” he cautioned.

He called “El Mudo” the “highest-ranking cartel guy on-site” during the attack.

“This guy is considered in our region, which is the north-west region [of Chihuahua], to be the top cartel dog, the top enforcer for the Juárez cartel,” he told The Guardian. “So it’s a pretty big deal locally.”