It seems like "defrauded" refers to those who got frauded. Then does the prefix "de-" implies the passive voice?

Native speaker’s answer
Rebecca
Actually, "defraud" means to get money from someone illegally through deception! But I can see why you'd think that. The prefix "de-," here, actually means "from," indicating getting the money "from" someone or something. The difference is that "fraud" is a noun, and "defraud" is the verb, the practice of lying to someone to get money. Ex: He committed fraud and was sent to prison. Ex: Some people try to defraud people online by pretending to be someone nice.