In question-answer sequences, I don’t know-responses (IDK-responses) are often considered to be dispreferred. How police officers handle these dispreferred responses in Chinese investigative interviews remains unclear. By adopting the method of conversation analysis, this study examines suspects’ IDK-responses and police officers’ management of these responses. It is found that suspects usually design their IDK-responses in two formats: stand-alone IDK and mitigated IDK. Changing topics, initiating repairs, reformatting questions and displaying explicit disbelief are those strategies frequently employed by police officers to manage suspects’ IDK-responses. These strategies do not necessarily elicit new information from the suspects. But except changing topics, the other three types of management formats can all provide suspects with opportunities to alter their original claims of insufficient knowledge. Suspects may produce accounts or further utterances to mitigate their prior IDK-responses or provide new answers to questions posed by police officers.