I'm sure this has been asked and answered before ... but who are the locked investigators?

I am compiling a comparison list of all the Arkham investigators and which games they appear in.

As I have yet to beat the last two expansions I still have 4 locked investigators.

Thanks

Rita Young (Azathoth campaign)

Leo Anderson (Cthulhu campaign)

Wendy Adams (Ithaqua campaign)

Luke Robinson (The Dark Pharaoh)

Thank you so much. I knew the game had relocked some of them on me and couldn't remember.....