If the browser bundle is literally the only thing on it, no bookmarks to SR, no text files with URLs or passwords, then that proves nothing. Even if there is a bookmark, that's something that good draw LE attention to watch you, but you couldn't be prosecuted for it. There are journalists and probably thousands of curious people who create SR accounts and don't buy anything. It's not illegal to browse the site. Tell her to give it back or you'll call the cops and report her for theft.