culprit /ˈkʌlprɪt/ /ˈkʌlprɪt/
criminal /ˈkrɪmɪnl/ /ˈkrɪmɪnl/
offender /əˈfendər/ /əˈfendə/
guilty /ˈgɪl.ti/ /ˈgɪlti/
blameworthy
at fault /æt fˈɑːlt/ /at fˈɒlt/