This paper explores 'other' ways of knowing DNA in the field of criminal investigation. Drawing upon 26 in-depth interviews with prisoners in Austria, it illustrates how this group knows and conceptualizes DNA traces and forensic DNA technologies. These understandings and conceptualizations are both nuanced and ambiguous. While on the one hand, DNA traces and forensic DNA technologies were not treated as categorically different from other types of traces and technologies in the prisoners' accounts, they were seen as 'unique' in one respect: respondents experienced DNA traces as beyond their control because they were virtually impossible to avoid (in contrast to, for example, fingerprints). Furthermore, the scientific rigour that our interviewees assumed to underpin forensic DNA technologies rendered these technologies as impenetrable and intimidating, and as effectively challenging many offenders' expert knowledge on how to manage crime scenes and avoid convictions. Finally, due to coming 'from the inside' of the body, forensic DNA technologies were seen as 'deepening' the stigma of delinquency in many of our interviewees' bodies and selves. For our interviewees, forensic DNA technologies assumed the role of institutionalized memories of their delinquency.