Book of Mormon Prophecies, Warner, pp. 151-153; New Witness for the Articles of Faith, McConkie, pp. 515, 599
“The lost tribes are not lost in the sense that we do not know where they are. The scriptures plainly tell us they have been scattered among every nation, kindred, tongue, and people. How then are they lost? They are lost temporally in the sense that they are in many instances lost to the lands of their inheritance. Of greater importance, they are lost in a spiritual sense: they are lost to the gospel and its saving ordinances, they are lost to the priesthood and all the blessings that flow from it… . They are so intermingled with the Gentiles of the world that they can only be identified by revelation—this revelation must come through ordained patriarchs, declaring to them their lineage and promised blessings as the chosen seed, but this only after they have found their way back to the fold of God… . Our Israelite forebears were scattered because they rejected the gospel… . They were scattered because they turned from the Lord… .” (R. Millet and J. F. McConkie, Doctinal Commentary on the Book of Mormon, 1:10)