This murder is best understood in the context of Cain. Cain was one of the sons of Adam and Eve. He was the older brother of Abel. By the time Cain and Abel were born there were many people on the earth - many children and descendants of Adam and Eve - but by this point many were wicked. It does not take people long to fall away from the truth and to become wicked, even degenerate. Here is the story as found in the book of Moses:
"And Adam and Eve blessed the name of God, and they made all things known unto their sons and their daughters. And Satan came among them, saying: I am also a son of God; and he commanded them, saying: Believe it not; and they believed it not, and they loved Satan more than God. And men began from that time forth to be carnal, sensual, and devilish. And the Lord God called upon men by the Holy Ghost everywhere and commanded them that they should repent; And as many as believed in the Son, and repented of their sins, should be saved; and as many as believed not and repented not, should be damned; and the words went forth out of the mouth of God in a firm decree; wherefore they must be fulfilled. And Adam and Eve, his wife, ceased not to call upon God. And Adam knew Eve his wife, and she conceived and bare Cain, and said: I have gotten a man from the Lord; wherefore he may not reject his words. But behold, Cain hearkened not, saying: Who is the Lord that I should know him? And she again conceived and bare his brother Abel. And Abel hearkened unto the voice of the Lord. And Abel was a keeper of sheep, but Cain was a tiller of the ground." (Moses 5:12-17).It is clear that many of Adam and Eve's children followed Satan. They had more children, hoping that they would follow their counsels and teachings. Many did not. Cain was not the first of the wicked children but he became one of the most wicked. Cain was a farmer, his brother Abel was a shepherd. Abel followed after the statutes and commandments of God. He was a righteous man who performed his sacrifices with exactness and honor.