Prior to the death of Brigham Young, blood atonement doctrine was taught primarily as a means for Mormon "covenant breakers" (usually adulterers and apostates) to pay for their sins, but a full list of sins requiring blood atonement was never given.
The practice of "blood atonement" was formally denied and repudiated by the church in a statement issued in 1889: MANIFESTO OF THE PRESIDENCY AND APOSTLES "SALT LAKE CITY, Dec. 12th, 1889.