When Melissa is pistol-whipped, her left cheek is cut. She then falls unconscious onto her right side, and later wakes up with her hands tied behind her in the same position. Gravity should have pulled the blood from the cheek wound toward her nose, but instead it is running toward her chin.
Andrea's plan to claim self-defense would be nullified once the medical examiner found the restraint marks on Melissa's wrists. This contrasts with the high level of planning and knowledge she displayed.