Personally, I'm thinking Sexton=Doctor Hurt.
He's hiding in plain sight and it would explain why he knows so much about the Black Glove and why he's investigating the group's murders. Also, the plotline about the possible embezzlement going on at Wayne Enterprises as far as it being something Hurt set up as a failsafe scheme to ruin Bruce and possibly bring him "out of hiding".
As for the Penitent, I'm thinking it would be the Joker, if he's gone sane in the wake of Batman's death.
