Does Mary Kate actually know what happened or does she just want attention?

So she is now saying she will not speak until she is granted immunity about Heath Ledger's death. What could she possible have to hide? Is she just doing this so the news will cover her and she will be talked about? She probably knows absoultely nothing about it, and jsut wants attention. It seems kind of unfair to withold information or act like you know something, his family has been through enough. What are your opinions on it?