Elder Joseph Standing, during his second mission to the Southern States, and while serving as president of the Georgia conference, was martyred on July 21, 1879, according to Andrew Jenson's LDS Biographical Encyclopedia, pp. 719-721.
Elder Standing's companion at the time of his death was Elder Rudger Clawson who would later serve in the Quorum of the Twelve.
According to the encyclopedia article, Elder Standing and Elder Clawson were surrounded by an armed mob near Varnells Station, Ga. When ordered by one of the mob to follow him, Elder Standing, "undoubtedly expecting that to follow him meant certain death, made some resistance, when a man who was near him pointed his pistol at him and fired. Elder Standing fell mortally wounded."
An order was then given to shoot Elder Clawson, but was never carried out, and he was allowed to go get help for Elder Standing.