If the killer threw himself before the Iron Throne, confessed to his crimes, and gave irrefutable evidence of his guilt, it wouldn't matter to Cersei. She won't rest until my head's on a spike. Not just yours. She's offering a knighthood to whomever finds Sansa Stark. Sansa couldn't have done this. She had more reason than anyone in the Seven Kingdoms. Do you think it's a coincidence she disappeared the same night Joffrey died? No, but Sansa's not a killer. Not yet, anyway.