At the beginning of Star Wars: Episode II when Padme is talking with Yoda, Mace Windu, etc., she claims to believe that Count Dooku was behind the assassination attempt; however, Windu defends Dooku in saying that it's not in his character and that he was once a Jedi.
PADME: I think that Count Dooku was behind it.
MUNDI: He's a political idealist, not a murderer.
WINDU: You know m'lady Count Dooku was once a Jedi. He couldn't assassinate anyone, it's not in his nature.
Why did Dooku 'resign' from being a Jedi?