One hundred fifty years ago, a glorious September morning in the Utah mountains morphed into Mormonism's darkest hour when a militia opened fire on a wagon train, leaving more than 120 men, women and children dead in a flowery field.

Now the "Mountain Meadows Massacre" is becoming more than a subject of somber reflection within tight-knit Mormon circles. Two new films and a forthcoming book aim to tell the nation what happened, why and -- perhaps most important -- whether the revered Mormon prophet Brigham Young ordered the killing....

"The important thing is to place the massacre in context," Helen Whitney, director of the PBS documentary, said in an interview. "They believed they were at war. The president was arriving with his troops. . . . All of this was swirling around -- years of persecution, a kind of paranoia -- it really was sort of an explosive mixture in which the brakes just didn't hold."

On the high-stakes issue of Young's role, the official view from the Mormon Church is simple: He had none. Young sent a messenger to tell militiamen to let the travelers pass without interference, said church spokesman Michael Otterson. The full case for vindicating Young will appear later this year in an Oxford University Press book written by three church historians.

Although Mormons regard themselves as Christians, orthodox Christians reject key tenets of Mormonism, such as the exaltation of founder Joseph Smith to the status of prophet and the treatment of his Book of Mormon as scripture. Despite being controversial, Mormons have risen to prominence in society. Mormons lead numerous well-known companies, occupy leadership positions in government and have a presidential hopeful in the GOP campaign of former Massachusetts governor Mitt Romney.

Some observers suspect a rising tide of anti-Mormonism accounts for today's intense focus on Mountain Meadows.

Jan Shipps, professor emeritus of religious studies and history at Indiana University-Purdue University Indianapolis and an expert on Mormonism, doubts that Young was involved in the massacre.

"My sense is that Brigham Young was not that dumb as to order people to kill a wagon train" and stir up more ill feelings toward Mormons, she said.

Nevertheless, she said, the prospect of implicating Young and his church in a historic tragedy appeals to modern-day critics.

"The important thing is, why is all this coming up right now?" Shipps said. Mormons used to live largely in the West, she says, but now "Mormons are everywhere. They are making converts that the evangelicals would like to make, so evangelicals are saying Mormons aren't Christian. All of a sudden you get this [attitude of]: We're going to look at Mormon history, and we're going to find out what's really there."