Fidel Alejandro Villegas Villegas is the director of public safety in Janos. He was the fourth person arrested in connection with the massacre

A Mexican police chief with apparent ties to the cartel has become the fourth person arrested in connection with the massacre of a US Mormon family earlier this year.

Fidel Alejandro Villegas Villegas is the director of public safety in Janos. He is believed to have ties to the La Linea cartel which is being blamed for the massacre against the LeBaron family in November.

According to The Herald of Chihuahua, he was arrested this week and is now being held in Mexico City.

The motive for the apparently 'targeted' attack remains unknown. The mayor of Janos said the police officer's involvement was a shock.

'It took us by surprise,' Sebastián Efraín Pineda said.

Brothers Héctor Mario and Luis Manuel Hernández were arrested earlier this month as was one other person who is yet to be named.

Three mothers and six children of the LeBarón family, all dual U.S-Mexican nationals, were shot dead and burned by suspected cartel gunmen on a remote dirt road in Bavispe, a town in the state of Sonora.

Seven other children survived the heinous November 4 ordeal - five of which were injured. They all were hidden for hours in the nearby brush while their two other siblings went looking for help.

Nine members of the family were killed and others were injured in the horrifying massacre

After they were shot, the families cars were set on fire. Some of their relatives are shown mourning them

The killings caused shock on both sides of the border, and increased pressure on Lopez Obrador's government to show it is acting against brutal violence by drug cartels.

The ambush occurred when three vehicles drove near the village of La Mora, around 70 miles south of Arizona, where members of the offshoot Mormon sect had lived since the last 1800s, after polygamy was outlawed in the United States.

When the killers struck, the three LeBarón families were spread out along a 12-mile stretch of road near the border of the two states at about 9:40am.

As bullets began to pummel the first car, a white Chevrolet Suburban, Christina Marie Langford Johnson, 29, stepped out waving her arms to show that they were not gang members.

The killings sparked protests against cartel violence throughout Mexico. Above, one demonstration on December 1

Christina was shot dead but her seven-month-old baby, Faith, survived the attack after her mother appeared to have placed her car seat on the floor before she got out.

Gunfire also ripped into a second white Suburban that was carrying Dawna Langford and nine children, about one mile back. Dawna and two of her sons, Trevor, 11, and Rogan, three, were killed.

Footage of the vehicle showed more than a dozen bullet holes in the roof and sides of the vehicle. Inside, blood was smeared across seats and children's toys.

A third car, 11 miles behind, was shot up and burst into flames, killing Rhonita María Miller and her four children - her eight-month-old twins, Titus and Tiana, her 10-year-old daughter Krystal and 12-year-old son Howard.

Miller, 30, was driving an SUV with four of her seven children when she reportedly suffered a flat tire while the family was on the way to pick her husband up from a Phoenix airport.

Before she could get help their car was caught in a hail of bullets, one of which struck the vehicle's gas tank.

Miller and four of her children were incinerated in their SUV after the vehicle exploded into flames.

Mexico's government has said it believes the victims were caught in the midst of a territorial dispute between an arm of the powerful Sinaloa Cartel and the rival Juarez Cartel.