Avard was born at St. Peter, Guernsey, Channel Islands. As an immigrant in the United States, he worked as a physician and later became a Campbellite minister in Pennsylvania. In 1835 in Freedom, Pennsylvania, Orson Pratt baptized him a member of Church of the Latter Day Saints and ordained him an Elder and leader of the local branch of the church. After serving a mission near his home with Erastus Snow, he moved to the Latter Day Saint community at Kirtland, Ohio in 1836. He was ordained a High Priest in 1837, though his position as a High Priest was also revoked that same year for unclear reasons.
In 1838, while living in Far West, Missouri and serving in the church's High Council there, Avard witnessed the heated conflict between the growing Mormon population and the established non-Mormon Missourians. He was the organizer and leader the Danites, a secret vigilante militia, bound by oaths and intent on retaliating for Mormon injuries and losses. It remains unclear the extent to which Joseph Smith was aware or in favor of Avard's activities, although he recognized the Danites and encouraged them to be lawful. Danite militaristic activities intensified the 1838 Mormon War and drew the attention of state government and militia.
After the Mormons were expelled from the Missouri and Joseph Smith was arrested, Avard was the chief witness against Smith, testifying that Smith was the mastermind behind the Danites. Smith denounced the group as "frauds and secret abominations" and excommunicated Avard in March 1839. Avard never attempted to return to the Latter Day Saints. By 1850 he was practicing medicine in Edwardsville, Illinois, where he died in 1869.
- Jessee, Dean C.; Ashurst-McGee, Mark; Jensen, Richard L., eds. (2008), "Biographical Directory", Journals, Volume 1: 1832–1839, The Joseph Smith Papers, Salt Lake City: Church Historian's Press, p. 398
- Some sources list 1803 as his birth year. See: "Mormon Biographical Register-A", Biographical Registers (BYU Studies), retrieved 2009-05-17
- From 1834 to 1838, the church founded by Joseph Smith was officially known as the Church of the Latter Day Saints. See Church of Christ (Latter Day Saints)#Early changes.
- (Bushman 2005, p. 351)
- (Bushman 2005, pp. 350, 352)
- (Bushman 2005, pp. 369, 372)
- "Mormon Biographical Register-A", Biographical Registers (BYU Studies), retrieved 2009-05-17
- Bushman, Richard Lyman (2005), Joseph Smith: Rough Stone Rolling, New York: Alfred A. Knopf, ISBN 1-4000-4270-4.