According to investigators, the church leaders purchased documents from Mr. Hofmann and then hid them in a vault with a number of 19th century letters and other documents that cast doubt on the church's official version of history.
New York Times, Feb. 11, 1987
—the gift of the discerning of spirits is poured out upon presiding officials in God's kingdom; they have it given to them to discern all gifts and all spirits, lest any come among the Saints and practice deception.— There is no perfect operation of the power of discernment without revelation. Thereby even 'the thoughts and intents of the heart' are made known.— Where the Saints are concerned— they Lord expects them to discern, not only between righteous and the wicked, but between false and true philosophies, educational theories, sciences, political concepts, and social schemes.
Apostle Bruce R. McConkie, Mormon Doctrine, p. 197
It has always been claimed that it is virtually impossible for a person to write a revelation that would compare with Joseph Smith's. It now appears, however, that there is someone [Hofmann] who can write revelations comparable to Joseph Smith's and that it is even possible to get them past the scrutiny of the highest leadership of the Mormon Church.
"Hofmann Talks!", The Salt Lake City Messenger, no. 64, Jan. 1987
"The Mormon Murders - Twenty-Five Years Later" by Sandra Tanner and Rocky Hulse
"Meet Mark Hofmann" - from mormoninformation.com
Mark Hofmann section on Debunking FairMormon