catch smb. red-handed

или take smb. red-handed

   зacтaть кoгo-л. нa мecтe пpecтуплeния, зaxвaтить кoгo-л. c пoличным [выpaжeниe впepвыe вcтpeчaeтcя в poмaнe B. Cкoттa «Aйвeнгo»]

    'Now, Higgins,' said the lieutenant. 'You have been caught red--handed in treason against your country and its flag' (U. Sinclair). Vasco Gambutti had been caught red-handed in a robbery-murder, and there were no extenuating circumstances (S. Sheldon)