In 1857 Mormon leader Brigham Young

In 1857 Mormon leader Brigham Young ordered the massacre of 100-140

In 1857 Mormon leader Brigham Young ordered the massacre of 100-140 emigrants on their way to California then covered it up from US federal investigators

The Mountain Meadows massacre was a series of attacks on the Baker–Fancher emigrant wagon train at Mountain Meadows in southern Utah. The attacks culminated on September 11, 1857, with the mass slaughter of most in the emigrant party by members of the Utah Territorial Militia from the Iron County district, together with some Paiute Native Americans.
The wagon train—composed almost entirely of families from Arkansas—was bound for California on a route that passed through the Utah Territory during a turbulent time period, later known as the Utah War. After arriving in Salt Lake City, the Baker–Fancher party made their way south, eventually stopping to rest at Mountain Meadows. While the emigrants were camped at the meadow, nearby militia leaders, including Isaac C. Haight and John D. Lee, made plans to attack the wagon train.
The militia, officially called the Nauvoo Legion, was composed of Utah’s Mormon settlers (members of The Church of Jesus Christ of Latter-day Saints or LDS Church). Intending to give the appearance of Native American aggression, their plan was to arm some Southern Paiute Native Americans and persuade them to join with a larger party of their own militiamen—disguised as Native Americans—in an attack. During the militia’s first assault on the wagon train, the emigrants fought back and a five-day siege ensued. Eventually fear spread among the militia’s leaders that some emigrants had caught sight of white men, and had likely discovered the identity of their attackers. As a result militia commander William H. Dame ordered his forces to kill the emigrants.
By this time the emigrants were running low on water and provisions, and allowed some approaching members of the militia—who carried a white flag—to enter their camp. The militia members assured the emigrants their protection and escorted them from the hasty fortification. After walking a distance from the camp, the militiamen, with the help of auxiliary forces hiding nearby, attacked the emigrants. Intending to leave no witnesses and to prevent reprisals to complicate the Utah War, the perpetrators killed all the adults and older children (totaling about 120 men, women, and children). Seventeen children, all younger than seven, were spared.
Following the massacre, the perpetrators hastily buried the victims, leaving the bodies vulnerable to wild animals and the climate. Local families took in the surviving children, and many of the victims’ possessions were auctioned off. Investigations, temporarily interrupted by the American Civil War, resulted in nine indictments during 1874. Of the men indicted, only John D. Lee was tried in a court of law. After two trials in the Utah Territory, Lee was convicted by a jury, sentenced to death, and executed.
Today historians attribute the massacre to a combination of factors, including war hysteria about possible invasion of Mormon territory, and strident Mormon teachings against outsiders. Scholars debate whether senior Mormon leadership, including Brigham Young, directly instigated the massacre or if responsibility lay with the local leaders in southern Utah.

Interactions with Mormon settlers
At the time of the Fanchers’ arrival, the Utah Territory was organized as a theocratic democracy under the lead of Brigham Young, who had established colonies along the California Trail and Old Spanish Trail. President James Buchanan had recently issued an order to send troops to Utah. Rumors spread in the territory about the motives for the federal troop movement. Young issued various orders, urging the local population to prepare for the arrival of the troops. Eventually Young issued a declaration of martial law.[4]The Baker–Fancher party chose to leave Salt Lake City and take the Old Spanish Trail, which passed through southern Utah. In August 1857, the Mormon apostle George A. Smith, of Parowan, traveled throughout southern Utah, instructing the settlers to stockpile grain. While on his return trip to Salt Lake City, Smith camped near the Baker-Fancher party on August 25 at Corn Creek, (near present-day Kanosh) 70 miles (110 km) north of Parowan. They had traveled the 165 miles (266 km) south from Salt Lake City, and Jacob Hamblin suggested that the wagon train continue on the trail and rest their cattle at Mountain Meadows, which had good pasture and was adjacent to his homestead.

While most witnesses said that the Fanchers were in general a peaceful party whose members behaved well along the trail, rumors spread about misdeeds. Brevet Major James Henry Carleton led the first federal investigation of the murders, published in 1859. He recorded Hamblin’s account that the train was alleged to have poisoned a spring near Corn Creek; this resulted in the deaths of 18 head of cattle and two or three people who ate the contaminated meat. Carleton interviewed the father of a child who allegedly died from this poisoned spring, and accepted the sincerity of the grieving father. But, he also included a statement from an investigator who did not believe the Fancher party was capable of poisoning the spring, given its size. Carleton invited readers to consider a potential explanation for the rumors of misdeeds, noting the general atmosphere of distrust among Mormons for strangers at the time, and that some locals appeared jealous of the Fancher party’s wealth