catch someone red-handed

US /kætʃ ˈsʌm.wʌn ˌredˈhæn.dɪd/
UK /kætʃ ˈsʌm.wʌn ˌredˈhæn.dɪd/
"catch someone red-handed" picture
1.

to discover someone in the act of doing something wrong or illegal

:
The police caught the thief red-handed as he was trying to break into the car.
My mom caught me red-handed eating cookies before dinner.