Mormon History, Jan 12, 1846

Parley P Pratt: ! accused by Orson Pratt the 12 Jan. 1846 before Twelve that while on mission he (Parley P Pratt ) would "seduce girls or females and sleep & have connexion with them contrary to the law of God," Parley P Pratt said this was a misunderstanding of cohabiting with plural wives, though he did not inform Brigham Young of an unauthorized relationship with Phoebe Soper

[source: Quinn, D. Michael, The Mormon Hierarchy: Origins of Power, Appendix 6, Biographical Sketches of General Officers of the Church of Jesus Christ of Latter-day Saints, 1830-47, http://amzn.to/origins-power]