Nine members of an American family were killed in Mexico on Monday while they were traveling to a wedding for an infamous family that has lived in Mexico for decades.

The victims, all women and children, were US citizens and members of La Mora, a Mormon settlement in the state of Sonora founded as an offshoot of The Church of Jesus Christ of Latter-day Saints, according to the Arizona Republic.

They were headed to a wedding in LeBaron, another Mormon community. LeBaron has deep roots in Mexico, including a dark past that involves a cult-like murder spree, drug cartel abductions, and polygamy.

The Church of Jesus Christ of Latter-day Saints has excommunicated many of the Mormon communities in Mexico due to their stance on polygamy. Still, the settlements continue to thrive across northern pockets of the country.

American Mormons first moved to Mexico to avoid polygamy crackdowns

The burned out car where nine family members of the La Mora Mormon Community died in Mexico. Lafe Langford Jr./Facebook

American Mormons first started settling in northern Mexico in the late 1800s. Groups first began migrating to the country because of a crackdown on polygamy in the United States. Mexico seemed like a haven at the time, a place where the group could continue practicing plural marriage.

The church's then-president, Brigham Young, first sent members to Mexico in 1875 to look for places to settle, according to the Mormon Encyclopedia available on Brigham Young University's website. Soon enough, hundreds, then thousands, traveled south.

While the Mormon church officially banned polygamy in 1890, it persisted in some communities, especially those in Mexico.

These sects, which the Church of Jesus Christ of Latter-day Saints later excommunicated, created their own offshoot settlements, including the La Mora settlement, in Bavispe, part of the Sonora state; Templo de Colonia Juarez in the state of Chihuahua; and LeBaron in Galeana, in Chihuahua.

According to a 2012 report from Vice, many Mormon communities appear extraordinarily rich to drug gangs, because of their large houses, manicured lawns, and golf courses.

Sen. Mitt Romney of Utah even has ties to Mexico — his family settled there in the late 1880s and lived in Chihuahua for decades. While Romney's direct family moved to Michigan, dozens of Romneys continue to live in the area.

Today, there are more than 1.4 million Mormons in Mexico, according to the church.

The LeBaron family has a dark past in Mexico, including a cult-like murder spree

The LeBaron community was one of the many Mormon settlements that persists in Mexico. It was founded by Alma Dayer LeBaron in 1944, according to Ruth Wariner, an author who fled the colony in the 1980s, when she was just 15 years old.

Her grandfather, Alma Dayer LeBaron, had been traveling back and forth from the US to Mexico for years and opened his colony as a place where people could practice what Wariner described as "Fundamentalist Mormonism," which supports aspects of Mormonism as it was taught in the 1800s, including polygamy.

Wariner said her father, Joel, later launched the Church of the Firstborn of the Fulness of Times, a sect of Fundamental Mormonism, and his brother, Ervil, became one of his first followers.

Polygamist leader Ervil LeBaron, pictured in June 1979. AP Photo

But Ervil started teaching an early Mormon doctrine called "blood atonement." He believed he had a right to kill those who have sinned in the name of God, starting with his brother, Alma.

Ervil LeBaron, who had 54 children and 13 wives, launched the Church of the First Born Lamb of God, using the distorted Mormon teachings.

Authorities say he and his followers committed at least 25 murders in Utah, California, Texas, Colorado, and Mexico, in the 1970s and 1980s, according to the Los Angeles Times.

Ervil died in 1981, but his followers continued to live out his prophecy for years, attempting to kill a list of targets Ervil had created before his death. Several members were arrested in the 1980s and 1990s, including his sons Haber LeBaron and Douglas Barlow.

Another one of his sons, Aaron LeBaron, was sentenced to 45 years in prison in a conviction connected to the murders.

In 2009, the LeBaron settlement was targeted by local drug cartels which kidnapped and murdered members of the community

In the years after the Church of the First Born Lamb of God murders, the LeBaron family started having disputes with drug cartels.

In 2009 16-year-old Eric LeBaron and his younger brother were abducted by a group of men with guns near the LeBaron settlement.

A woman holds a picture of Mormon anti-crime activist Benjamin LeBaron, left, and his neighbor Luis Widmar, who were killed in 2009. AP Photo

The kidnappers demanded $1 million for the brothers' release, according to the Houston Chronicle. The village led protests of hundreds of people against government officials in Chihuahua, asking for soldiers and police officers to search for the victims. The boys were released four days later, without the kidnappers receiving any money.

But just months later, Eric's older brother Benjamin and his brother-in-law, Luis Widmar, were killed by gunmen. Benjamin LeBaron had led the government protests pushing for Eric's release and demanded police protection for their community. Drug trafficker Jose Rodolfo Escajeda was later arrested for their murders.

The recent murders may have been a case of mistaken identity

In recent weeks, Mexico has been hit with a wave of violent attacks, including a military-style cartel assault that forced the government to release a leader of the Sinaloa Cartel in October.

The killing of nine members of a Mormon family on Monday, say relatives, may have been a case of mistaken identity.

The vehicles were found wholly burned out and covered in bullet holes. Family members told NBC News that eight people survived the attack, but several are missing and may have been kidnapped.

Sonora state Gov. Claudia Pavlovich Arellano said she was outraged by the attack on the family.

"As a mother, I feel anger, scorn, and a profound pain for the cowardly events in the mountains between Sonora and Chihuahua," she tweeted. "I don't know what type of monsters would dare to hurt women and children. As governor, you have all my collaboration so that this doesn't remain unpunished, and the responsible parties pay."

A previous version of this story said polygamy was banned in the Mormon Church in 1980. That has been amended to 1890. A previous version of this story said Ervil LeBaron died in 1956. He died in 1981.