One Piece Chapter 46, page 16: The Uninvited Guest

Patty angrily explains Krieg's notorious reputation to Sanji: "The ruler of East Blue, the king of deceptions! That's Don Krieg for you! He started out by disguising as a Marine after escaping from prison! He then killed the Marine officer in charge of the ship and took it over! That's how he became a pirate! Since then, he's attacked ports, towns, and other ships by hanging a Marine flag... And when attacking his enemies, he hangs a white flag to attack them by surprise...! He's a man who'll stoop to anything in order to win! And that's how he made his way to the top! His strength ain't no exaggeration either! You really think he'll just leave after eating!? That's utterly impossible for him! Letting a demon like him starve to death, is for the good of this world!!"