Sanders was among a gathering of booksellers, historians, authors and massacre descendants gathered in Salt Lake City last week by the AP for a private screening of the movie arranged in cooperation with filmmakers. LDS Church officials, including church historians working on a book about the massacre, were invited to the screening but declined to attend. Spokeswoman Kim Farah said the church plans no comment about the movie once it opens.

The film drew a somber and emotional reaction, including a few tears from descendants of the 17 survivors, who said their side of the story has rarely been told.

"Speaking for the victims, it's taken 150 years of this before any type of movie about this to come out. ... We appreciate it," said Phil Bolinger, of Hindsville, Ark., who is related to 30 of those killed.

With its "R" rating, many Mormons may not even see the film, bookseller Curt Bench said. Those who do may walk out, irritated by what Bench and others said was a stereotypical, one-dimensional portrait of blindly obedient church members that bordered on cartoonish at times. A scene that includes a sacred Mormon temple ceremony will also offend.

"I think it went a little too far in making the Mormons bad, bad, bad and the immigrants good, good good," said Leroy Lee, a Mormon and the great-great-grandson of John D. Lee.

"I think if you were someone in the Fancher party and this happened to you ... this is what you saw," countered Mormon filmmaker Richard Dutcher ("God's Army").

And that's what separates Cain's account from many other versions of the story.

"The new part that this film brings out is that the Fanchers were probably pretty decent people just trying to get to California," Mormon History Association spokesman Tom Kimball said. "That's the first time that's ever been presented to me as a Latter-day Saint."

Past portrayals of the massacre suggested the Fancher party "brought it on themselves," Kimball said.

"Here's a story that has not been accurately portrayed and has been sequestered by my people, and it's very important that this story is finally told," he said.

Cain said the movie is not meant to offend, nor be a portrait of Mormons in general.

"The Mormons that were involved in this specific event were bad," he said. "We didn't do a movie about the Mormon church. We did it about the specific event and the people involved."

If Cain erred in some specifics, he may have come close in trying to establish the climate of persecution that spurred distrust of outsiders among Mormons at the time. Then a territory, Utah was at odds with the federal government over the issues of polygamy and Young's theocratic rule. The U.S. Army was marching west to remove him as governor.