Jason Mittell has proposed “forensic fandom” as a mode of television engagement that encourages research, collaboration, analysis and interpretation (2009, 2015). Although Mittell discusses fans of the TV show Lost, the idea of forensic fandom with its emphasis on obtaining, scrutinizing and displaying media as evidence in order to prove a point has other applications. Not least for true crime fandom.

True crime fans are no strangers to analyzing cases, uncovering evidence and occasionally exonerating those already convicted. The emergence of fan communities as a result of both the highly successful Serial podcast and the Netflix documentary Making a Murderer demonstrate the ways in which changing digital technologies and changing audience/producer relationships can combine to create a community that blurs the boundaries between engaged fandom and citizen investigation. This chapter is interested in how these practices converged in the Gabby Petito case, which went viral thanks to TikTok users posting videos speculating over her disappearance and subsequent death. Through an analysis of social media content, including TikTok videos and Reddit posts, I examine the processes through which those investigating Petito's disappearance moved from interested observers to active participants. I suggest that, while true crime has always generated an active audience, social media aligns this more closely to fandom. Users engaged with Petito's social media posts and those shared by other users to find clues, used digital resources, such as All Trails to analyze real-word locations and digital artifacts, and suggested alternative theories akin to those used by fans of ongoing television shows. Furthermore, these practices happened in real time, treating Petito's disappearance like an evolving narrative which only ended once her fiancé's confession was released to the public.