in flagranteadverb
uk/ˌɪn fləˈɡræn.teɪ//ˌɪn fləˈɡræn.teɪ/also in flagrante delicto, /ɪn fləˌɡræn.teɪ dəˈlɪk.təʊ//ˌɪn fləˌɡræn.teɪ dəˈlɪk.toʊ/in the act of doing something wrong, especially having sex with someone who is not your husband, wife, or usual partner:
She returns home early to find her husband in flagrante delicto with a neighbour.