noun
suspicious person; suspicious-looking individual
Refers to a person whose behavior or appearance seems suspicious, often used in security contexts or by police.
近所で不審者が目撃された。
A suspicious person was spotted in the neighborhood.
警察が不審者を追いかけている。
The police are chasing a suspicious individual.
怪しい人 is a more colloquial and broader term for a suspicious or shady person, while 不審者 is more formal and often used in official warnings.
Compound of 不審 (ふしん, 'suspicion, doubt') + 者 (しゃ, 'person').