fair cop

it's a fair cop {UK sl} — (an admission that the speaker has been caught red handed; just after being caught at something, roughly equivalent to "Yes, I did it." From "cop", to catch; used humorously when someone has discovered that you have done something wrong and you want to admit it.) — застукали на месте; ваша взяла;....

a fair cop
обоснованный арест; попался за дело, поймали с поличным

Example 1: It's a fair cop. I was driving way too fast.

Example 2: All right, I admit it. That's a fair cop — Хорошо, я должен признать, что ваша взяла.(Gl)

Example 3: And criminals are warned that from then, they won’t even have time to tell police it’s a fair cop.

Example 4: The attitude of the professional thief is quite different. If he's nabbed it's a fair cop, he pleads guilty and hopes to be smarter next time — Отношение у профессионального вора совсем другое. Если он попался, то все по закону. Он признает себя виновным и надеется впредь быть умнее /ловчее(Gl)

Example 5: She bowed gracefully to a fair cop — Она великодушно признала, что ее застукали с поличным.

see also
[catch sb in the act]
[catch sb with one's pants down]
catch sb red-handed

already got one paw on the chicken coop (got caught in the act of doing something bad or wrong {US})