Times and Seasons article mentions Caswall's visit with Joseph.
"Reward of Merit," Times and Seasons 4, no. 23 (October 15, 1843): 364–365
It will be recollected by some, that a Mr. Caswell, professing to be an Episcopal minister, came to this city some twelve or eighteen months ago. He had with him an old manuscript, professing to be ignorant of its contents, and came to Joseph Smith, as he said, for the purpose of having it translated. Mr. Smith had a little conversation with him and treated him with civility, but as the gentleman seemed very much afraid of his document, he declined having any thing to do with it.
The Rev. gentleman afterward published a book, informing the inhabitants of the earth, that he had been to Nauvoo, and had seen the prophet—had conversed with the Mormons, and had heard a Mr. Kilbourne, a very conspicuous character in our neighborhood, (and who, according to Mr. Caswell's account, had been robbed of more than half the inhabitants of Iowa, possessed by the Mormons,) relate many wonderful stories;—after telling all the tales that he had heard, went to making others in regular Episcopal order out of whole cloth, and published his misshapen batch to the world, as a 'History of Mormonism.' Thus as a reward of merit for publishing detraction and falsehoods already concocted, and adding a very splendid edition of his own, he has proven himself worthy of being exalted to the honor of bearing the sacerdotal robes, and of being raised to the very high and dignified office of curate (!!!!) in the English church. He has truly gained himself unfading laurels, and by continuing in well doing, and assisting some of the Rev. blackguards, whom the church of England have employed in England to abuse the Mormons, he may perhaps gain further honors. The following we clip from the Chicago Democrat:
"The Rev. Mr. Caswell, author of the 'History of the Mormons' late of the American Episcopal Church, has been admitted to the privileges of the English Church, under the provisions of a special act of parliament. He has also been appointed to a curacy.'