JFS discusses firing squads in Utah and blood atonement.
Joseph F. Smith, Jr. and Richard C. Evans, Blood Atonement and the Origin of Plural Marriage: A Discussion (Independence, MO: Zion's Printing and Publishing Company, 1905), 15-16.
In pursuance of, and in harmony with this scriptural doctrine, which has been the righteous law from the days of Adam to the present time, the founders of Utah incorporated in the laws of the Territory provisions for the capital punishment of those who wilfully shed the blood of their fellow man. This law, which is now the law of the State, granted unto the condemned murderer the privilege of choosing for himself whether he die by hanging, or whether he be shot, and thus have his blood shed in harmony with the law of God, and this atone, so far as it is in his power to atone, for the death of his victim. Almost without exception the condemned party choses the latter death. This is by the authority of the law of the land, not that of the Church. This laws was placed on the statues through the efforts of the "Mormon" legislators, and grants to the accused the right of jury trial. It is from this that the vile charge, which you are pleased to repeat, has been maliciously misconstrued by the enemies of the Church, who prefer to believe a lie. When men accuse the Church of practicing "blood atonement" on those who deny the faith, or, for that matter, on any living creature, they know that they bear false witness, and they shall stand condemned before the judgment seat of God.