In this paper I discuss the many complexities that police officers have to deal with in their communication with suspects. Investigative interviewing is a very complex communicative situation in itself, with a number of different psychological and sociological variables at play during each interview. In addition, suspect interviews bring about an additional dimension of complexity, which is driven by the fact that a basic principle of conversation, cooperation (Grice 1975) is often not respected and is sometimes severely and purposefully violated, for example when suspects are guilty and want to obscure that very fact or when they believe that their situation would worsen if they cooperated with the police. A further layer of complexity is added when the interviews are carried out via an interpreter, where the fact that the officer and the suspect speak different languages during the interview creates additional barriers to straightforward communication. In the present paper, I identify a number of points at which communication difficulties are encountered in this highly sensitive legal context. For this purpose, I analyse authentic interview datasets provided by two UK police constabularies, and also make comparisons with examples from transcripts of authentic US police interrogations. In addition, I highlight the issues that arise when professional interpretation is not available and when bilingual police officers assume the dual role of investigator-interpreter. Finally, I suggest possible solutions that can help remove the hurdles standing the way of efficient and accurate gathering of communication evidence.