SACRAMENTO — Researchers with the LDS Church's historical department say conflicting accounts and missing documents have vexed historians looking to determine exactly how the Mountain Meadows Massacre came about and who had prior knowledge of the plan to murder about 140 men, women and children in southern Utah.

Speaking at the annual conference of the Mormon History Association on Friday, a trio of researchers shared details about documents — and their historic interpretation — surrounding questions that remain and may never be answered definitively.

Brian Reeves told the audience in a packed conference room about documents relating to the massacre that have either been "lost, suppressed or destroyed." He began by noting that prior to the publication of Juanita Brooks' 1950 book on the massacre, she was "denied access to relevant documents by the (church's) First Presidency," which will be detailed in a book to be released this summer by LDS historians.

"Massacre at Mountain Meadows" is scheduled for release in July, according to researchers who helped examine and look for documents, some of which were known to exist at some point but have disappeared.

The appendix in Brooks' book contains the transcript of a deposition by Brigham Young during the second trial of John D. Lee, the only man ever convicted of participating in the massacre. Young said he received a letter from Isaac Haight, a stake president in southern Utah, a few days before the massacre but that he did not have it at the time of the deposition. He told the questioner he had "made a diligent search for it but cannot find it," Reeves said.

Another document known to exist but which subsequently disappeared chronicled the testimony of William Dame, a southern Utah church leader who authorized the massacre in September 1857. He gave testimony regarding the events, which was recorded in full when two LDS apostles were in southern Utah in 1858 asking about the events. But the surviving record of testimony taken at the Dame hearing "contains only condensed minutes" of the testimony. "We don't know what became of his full account," Reeves said.

Another document known to exist was a roster that members of the ill-fated Fancher wagon train drew up while they were staying at Mountain Meadows, including an itemized list of their property. The immigrants were apparently "hoping it would reach California" in the event they did not, Reeves said.

The letter was found near a murdered man after the massacre and was at some point apparently destroyed, though an LDS leader in southern Utah, Jacob Hamblin, was "acquainted with the nature of its contents. He possessed the letter for a time," Reeves said.