With hundreds of millions of users worldwide, forensic data extraction from social networks has become an important research problem. However, forensic data collection is tightly connected to social network operators, which leads to problems related to data completeness and data compatibility. This paper discusses the important data sources and analytical methods for the forensic analysis of social networks. It shows how the data sources can be evaluated in an automated fashion without assistance from social network operators. While the proposed methods apply to the vast majority of social networks, their feasibility is demonstrated using a Facebook case study.