Millions of human biological samples are stored worldwide for medical research or treatment purposes. These biospecimens are of enormous potential value to law enforcement as DNA profiles can be obtained from these samples. However, forensic use of such biospecimens raises a number of ethical questions. This article aims to explore ethical issues of using human bodily material in medical biobanks for crime investigation and prosecution purposes. Concerns about confidentiality, trust, autonomy and justice will be discussed. We explore how to balance these concerns against the importance of crime solving. Relevant case examples of forensic use of medical biobanks show that requests by law enforcement to access biobanks are handled in disparate ways. We identify some core ethical issues and conclude that further research on these issues is needed to provide ethical guidance.