Background: Gangstalking refers to a novel persecutory belief system wherein sufferers believe that they are being followed,
watched, and harassed by a vast network of people in their community who have been recruited as complicit perpetrators. They
are frequently diagnosed as mentally ill, although they reject this formulation. Those affected by this belief system self-identify
as targeted individuals (TIs). They seek to prove the veracity of their persecution and dispute the notion that they are mentally
ill by posting videos online that purport to provide evidence of their claims.
Objective: The objective of the study was to characterize the multimodal social semiotic practices used in gangstalking evidence
videos.

Methods: We assembled a group of 50 evidence videos posted on YouTube by self-identified TIs and performed a multimodal
social semiotic discourse analysis using a grounded theory approach to data analysis.
Results: TIs accomplished several social and interpersonal tasks in the videos. They constructed their own identity as subjects
of persecution and refuted the notion that they suffered from mental illness. They also cultivated positive ambient affiliation with
viewers of the videos but manifested hostility toward people who appeared in the videos. They made extensive use of multimodal
deixis to generate salience and construe the gangstalking belief system. The act of filming itself was a source of conflict and
served as a self-fulfilling prophecy; filming was undertaken to neutrally record hostility directed toward video bloggers (vloggers).
However, the act of filming precipitated the very behaviors that they set out to document. Finally, the act of filming was also
regarded as an act of resistance and empowerment by vloggers.

Conclusions: These data provide insight into a novel persecutory belief system. Interpersonal concerns are important for people
affected, and they construe others as either sympathetic or hostile. They create positive ambient affiliation with viewers. We
found that vloggers use multimodal deixis to illustrate the salience of the belief system. The videos highlighted the Derridean
concept of différance, wherein the meaning of polysemous signifiers is deferred without definitive resolution. This may be
important in communicating with people and patients with persecutory belief systems. Clinicians may consider stepping away
from the traditional true/false dichotomy endorsed by psychiatric classification systems and focus on the ambiguity in semiotic
systems generally and in persecutory belief systems specifically.