Nisarg Shah, an associate professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at UC San Diego’s Jacobs School of Engineering, was targeted in a vigilante sting coordinated by online activists using the Instagram handles @timjohnson.458 and @vans_against_predators. The confrontation, which took place on Saturday, August 2, inside Pavilions grocery store in San Diego's Hillcrest community, was published with a watermark from the group "People v Preds".
In the video, activist Tim Johnson - who claims to have exposed more than 500 suspected predators - confronts Shah over explicit chats that allegedly took place on the Grindr dating app. Screenshots shared by the activists appear to show Shah identifying himself as 28 years old and engaging in sexually explicit conversations even after the decoy stated he was "bout to be 15."
During the in-person confrontation, Shah repeatedly expresses remorse, stating he feels "horrible, the worst I’ve ever felt," and describes his own conduct as "abhorrent." In a longer segment of the video recorded outside the store, Shah admits to bringing personal lubricant and a douche, claiming it was intended to help the person he thought he was meeting "get ready" and "prep." He repeatedly states, "I fucked up," and adds, "I need to maybe get help or something."
Two San Diego Police Department patrol cars arrive during the encounter. On video, an SDPD officer informs the activists that Shah would not be arrested at the time, explaining that he was "not allowed to arrest him" under the circumstances, though Shah's phone would be seized and the evidence provided to the Internet Crimes Against Children (ICAC) Task Force. A photo appears to show Shah in handcuffs, but he was reportedly released at the scene.
In response to our inquiry, SDPD Lt. Travis Easter provided the following statement:
"We are aware of the incident and our ICAC unit is actively investigating it. There have not been any charges made as of yet. Our ICAC unit will typically not work with civilians acting as undercover operatives and does not condone such activities because the training involved to conduct these investigations consists of hours of intense legal training. Without that training, well-meaning civilians not only endanger themselves, but also the person they are contacting, as well as the general public."
UC San Diego also responded, writing:
"We have been made aware of the allegations against Nisarg J. Shah. We will cooperate with all law enforcement agencies as needed during any investigation. The health, well-being and safety of our campus community members is our top priority. All allegations of sexual harassment and sexual violence are taken very seriously. Anyone experiencing harassment, discrimination, sexual and relationship violence or stalking is encouraged to reach out to UC San Diego's Office for the Prevention of Harassment and Discrimination at [email protected] or ReportBias.ucsd.edu."
Shah himself responded to our request for comment with the following statement:
"These are wrongful allegations and while I would have been willing to share my account, my attorney will not let me do so but he would be happy to speak with you."
Shah is a respected academic specializing in immunoengineering and nanoscale materials. He earned his Ph.D. from MIT and completed a postdoctoral fellowship at Harvard University before joining UCSD, where he teaches and leads a research lab. The incident has provoked widespread outrage across social media, with users demanding that UCSD investigate and take disciplinary action.
This is a developing story and will be updated as more information becomes available.
Originally published on August 3, 2025. Updated on August 4, 2025.
