Richard E. Turley, Jr. reports on a forged document clearly connecting Sidney Rigdon and Solomon Spaulding made by Mark Hofmann.
Richard E. Turley, Jr., Victims: The LDS Church and the Mark Hoffman Case (Monee, IL: Anvil & Cross, 2021), 125-126, 238
The following day at 9:30 A.M., Hofmann visited Pinnock in his office and showed him a document he said was from the McLellin collection. It was an 1822 deed signed by several persons, including Solomon Spalding and Sidney Rigdon. Pinnock asked if he could make a photocopy of it. Hofmann consented on condition that Pinnock keep the document confidential and not distribute it. Pinnock agreed. Noting the meeting in his journal, Pinnock described the document as "interesting but not significant beyond a historical connection." He felt that though the document might prove Spalding and Rigdon knew each other, it did not prove Spalding had influenced the writing of the Book of Mormon.
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Pinnock again went over his journal entries, supplementing them with recollections. As he spoke, his visitors interrupted to ask questions and add occasional insights from their investigation. When Pinnock described the Spalding-Rigdon document that Hofmann allowed him to copy the previous July 14, his visitors said the document was originally dated 1792 and then altered to 1822. Also, they said, the Spalding who puruportedly signed the document died in 1816, making it impossible for him to have signed it six years later. Furthermore, they said, he preferred spelling his name "Spaulding."