noun
flagrante delicto; caught red-handed
Refers to being caught in the act of committing a crime. Often used in legal or news contexts, but also in everyday speech for being caught doing something wrong.
彼は万引きをしているところを現行犯で逮捕された。
He was arrested red-handed for shoplifting.
現行犯でなけれ
In some cases, you can't make an arrest unless it's flagrante delicto.