Why did Joseph's brothers really try to kill him? While biblical scholars have long attributed their murderous plot to sibling rivalry, favoritism, and jealousy over prophetic dreams, close textual analysis reveals a more immediate trigger: they feared Joseph would expose their illicit activities. Through examination of biblical narrative structure, geographical details, and linguistic clues, this research reconstructs the brothers' circumstances and decision-making process. Their deliberate relocation from Shechem to Dothan, combined with their instant conspiracy upon spotting Joseph's approach, suggests panic at potential discovery of wrongdoing rather than mere fraternal resentment. Though the brothers indeed harbored grievances over Joseph's dreams and their father's partiality, these longstanding tensions alone did not precipitate the murder attempt. Instead, Joseph's established role as an informant and the brothers' fear that he would report their unauthorized location and probable misconduct to Jacob emerged as the decisive factor. This defensive motivation—silencing a witness rather than eliminating a rival—offers new perspectives on the narrative's dramatic structure and moral complexity.