Genesis 4:8-10

Cain talked with Abel his brother [about what God had said]. And when they were [alone, working] in the field, Cain attacked Abel his brother and killed him. [1 John 3:12] Then the LORD said to Cain, “Where is Abel your brother?” And he [lied and] said, “I do not know. Am I my brother’s keeper?” The LORD said, “What have you done? The voice of your brother’s [innocent] blood is crying out to Me from the ground [for justice]. [Num 35:33; Deut 21:1-9]