John Whitmer served as one of a handful of scribes while Joseph and Oliver continued the translation of the Book of Mormon in the Whitmer home. Joseph singled out John among the Whitmer family, writing that “John Whitmer, in particular, assisted us very much in writing during the remainder of the work” (JS History, 1838–1856, vol. A-1, 22, JSP). John was later chosen to serve as one of the eight witnesses of the Book of Mormon. During an interview John gave in April 1878 to P. Wilhelm Poulson, a reporter from the Deseret News, he recounted the following details of his experience as one of the witnesses:

I (Poulsen) – I am aware that your name is affixed to the testimony in the Book of Mormon that you saw the plates?

He (John Whitmer) – It is so, and that testimony is true.

I – Did you handle the plates with your hands?

He – I did so!

I – Then they were a material substance?

He – Yes, as material as anything can be.

I – Were they heavy to lift?

He – Yes, and as you know gold is a heavy metal: they were very heavy.

I – How big were the leaves?

He – So far as I recollect, 8 by 6 or seven inches.

I – Were the leaves thick?

He – Yes, just so thick, that characters could be engraven on both sides.

I – How were the leaves joined together?

He – In three rings, each one in the shape of a D with the straight line towards the center.

I – In what place did you see the plates?

He – In Joseph Smith’s house; he had them there.

I – Did you see them covered with a cloth?

He – No. He handed them uncovered into our hands, and we turned the leaves sufficiently to satisfy us (in Ron E. Romig, Eighth Witness: The Biography of John Whitmer, 2014, 526).

The Lord later called John to serve as Church historian and recorder (D&C 47). John was responsible for copying many of Joseph Smith’s early revelations. A document in possession of Community of Christ containing characters from the plates also appears to have been created by John Whitmer (see Michael Hubbard MacKay, Gerritt J. Dirkmaat, and Robin Scott Jensen, “The Caractors” Document: New Light on an Early Transcription of the Book of Mormon Characters, Mormon Historical Studies 14, no. 1, 131–51).

John continued to serve in the Church until 1838. During this time, the entire Whitmer family became embroiled in controversy. The Missouri High Council excommunicated John from the Church on March 10, 1838, for charges of “unchristian like conduct” with the record of his trial noting that he and others “be given over to the buffetings of Satan, until they learn to blaspheme no more against the authorities of God, nor fleece the flock of Christ” (Minute Book 2, 107, JSP). Though he left the Church and never rejoined, John never denied his testimony of the Book of Mormon. Near the end of his life, he was interviewed by Myron Bond, who later wrote, “Old Father Whitmer told me last winter with tears in his eyes, that he knew as well as he knew he had an existence that Joseph translated the ancient writing which was upon the plates which he saw and handled” (Saints’ Herald, 15 August 1878, 253).