I think this may be the reason this murder was “forgotten”. From Wikipedia:
Alberta King was shot and killed on June 30, 1974, at age 69, by Marcus Wayne Chenault, a 23-year-old black man from Ohio who had adopted an extremist version of the theology of the Black Hebrew Israelites.[4] Chenault’s mentor, Rev. Hananiah E. Israel of Cincinnati, castigated black civil rights activists and black church leaders as being evil and deceptive, but claimed in interviews not to have advocated violence.[5] Chenault did not draw any such distinction, and actually first decided to assassinate Rev. Jesse Jackson in Chicago, but canceled the plan at the last minute. Two weeks later he set out for Atlanta, where he shot Alberta King with two handguns as she sat at the organ of the Ebenezer Baptist Church. Chenault said that he shot King because “all Christians are my enemies,” and claimed that he had decided that black ministers were a menace to black people. He said his original target had been Martin Luther King, Sr., but he had decided to shoot his wife instead because she was near him. He also killed one of the church’s deacons, Edward Boykin, in the attack, and wounded another woman.
Alberta King was interred at the South View Cemetery in Atlanta. Martin Luther King, Sr., died of a heart attack on November 11, 1984, at age 84 and was interred next to her.
Conviction and sentencing
Chenault was convicted of first-degree murder and sentenced to death. The sentence was upheld on appeal, but he was later resentenced to life in prison, partially as a result of the King family’s opposition to the death penalty. On August 3, 1995, he suffered a stroke, and was taken to a hospital, where he died at age 44 of complications from his stroke on August 19.[6][7]