罪魁禍首

罪魁祸首
zuìkuíhuòshǒu
(idiom) criminal ringleader; main offender; main culprit; main cause of a disaster

CEDICT

Entry Composition

1 罪魁 zuìkuí
  1. criminal ringleader
  2. chief culprit
  3. fig. cause of a problem
2 禍首 huòshǒu
  1. chief offender
  2. main culprit