Harry ignored the ditzy girl. "Well, one thing's for sure. Hagrid didn't do it, but he got framed for it. A Basilisk is totally different from an Acromantula anyway."
"Wait," Su said suddenly, "Then what about Tom Riddle? Unless he was the one who..."
"Framed Hagrid." finished Tracey.
"They couldn' prove it." Hagrid said gruffly. "Tom was a prefect, so they believed him. Not me. Only Dumbledore didn'... great man, Dumbledore."
Tracey met Harry's eyes. "You thinking what I'm thinking?"
"If you mean Tom was the Heir of Slytherin, then yes." Harry said casually. So now it's just an issue of getting people to follow the right track.
Su frowned. "But I've never heard of a pureblood family named Riddle."
"He could be a halfblood with the surname of his Muggle parent." Luna volunteered. "After all, Professor Snape is the same."
"What? Professor Snape isn't a pureblood?" Tracey seemed shocked at the bit of information, and she wasn't the only one.
Funny, isn't it? The Head of the House of Pureblooded Bigots isn't a pureblood... Harry's expression darkened momentarily. Acts like one though...