and whether this is because they could not see their dead brothers , or because , having murdered them ( one apiece , save septimus , who had killed both quintus and sextus , poisoning the former with a dish of spiced eels , and , rejecting artifice for efficiency and gravity , simply pushing sextus off a precipice one night as they were admiring a lightning storm far below ) , they chose to ignore them , scared of guilt , or revelation , or ghosts , their father did not know .