who told umbridge about dumbledore's army in the book
Dumbledore's Army When Cho's friend Marietta Edgecombe betrays the group to Umbridge (Cho herself while under the influence of the truth potion Veritaserum in the film), Marietta is cursed with pimples on her face as a result of Hermione's casting a spell on the D.A. membership list. Later on, to prevent Harry's expulsion and the incrimination of other members, Dumbledore claims responsibility for organising the group, then escapes when Ministry officials attempt to arrest him. Though the D.A. stops meeting following these events, three members — Ginny, Neville and Luna — join Harry, Ron and Hermione in the battle in the Department of Mysteries towards the end of the fifth book. In Harry Potter and the Half-Blood Prince, Neville and Luna are distraught due to the fact that the D.A. no longer exists. When Hogwarts is invaded by Death Eaters, they are among the members who join the Order of the Phoenix in the ensuing battle.