Visual content like digital images and videos are helpful in forensic investigation, which usually provides direct evidence. However, the privacy issues arising therefrom are rarely addressed. In this paper a partial encryption based scheme is proposed to enable privacy-preserving forensics for JPEG images. Viewing sensitive regions, e.g. human faces, is only granted by the trusty party when the content is proved to be of potential relevance to the investigation. A key management protocol is defined for access authorization, which ensures access to the restricted content only possible under agreement by pre-defined parties. A fully reversible partial encryption approach is applied to ensure that the encrypted regions can be perfectly recovered after the decryption is approved. Evaluation results demonstrate the applicability and effectiveness of the proposed scheme.