"He was the last person to see Dumbledore alive, you know. It's logical that someone question the boy about his involvement. He must know more than he said before," he told her, keeping an eye on her as they walked. "A great wizard such as Dumbledore doesn't just fall over the edge of a building on his own."
And it galled Xavier that Severus was being lauded a hero. It was pathetic. The idiot half-blood could have - should have done away with the meddlesome old fool years ago.