wrongdoerformal
a fact or situation that is the reason for something bad happening: 问题的起因；罪魁祸首
Children in this country are getting much too fat, and sugar and sweets are the main culprits.该国儿童过于肥胖，糖和甜食是罪魁祸首。

SMART Vocabulary: related words and phrases

Criminals - general words
abettor
accessory
accomplice
anti-gang
be in the frame (for something)idiom
crook
delinquent
gangland
juvenile delinquent
lawbreaker
lowlife
malefactor
perpetrator
previous
probationer
recidivist
stalker
wanted
white-collar criminal
wrongdoer

You can also find related words, phrases, and synonyms in the topics:

Reasons and explanations

culprit | American Dictionary

culprit
noun[ C ]
us/ˈkʌl·prɪt/
someone who has committed a crime or done something wrong:
Two eyewitnesses identified her as the culprit.
A culprit is also anything that causes harm or trouble:
The culprit was identified as a microorganism that contaminated mayonnaise.