Far less patiently, Rita snaps back, "How the hell would I know what's going through your head?!"

After a moment, though, she does at least answer the question--not that it necessarily means she thinks the culprit is someone else! "I planted it, of course. Put a spell on it and left it as bait, and the idiot took it." Her gaze flickers to the magnet, then back to Cassandra's eyes: see, and now the bait has made its way here, her expression practically says.