MADISON, Wis. — UW–Madison police are investigating video released by a recent graduate who says he secretly entered the university’s Meat Science & Animal Biologics Discovery Building and recorded pigs undergoing carbon dioxide stunning, a process used to render animals unconscious before slaughter. Ryan Blum, who graduated in May and identifies as an animal-rights activist, told WMTV he spent months planning the entry after noticing liquid carbon dioxide tanks behind the facility in 2024. He said publicly available information, including an online tour of the building, helped him understand the layout before he entered. Blum said he recorded about 83 seconds of video, fewer than 30 seconds of which show pigs inside what he describes as a carbon dioxide chamber. The footage is dark, includes few identifying details and contains pig vocalizations. Neither UW–Madison nor WMTV independently verified that the video was recorded at the university facility. The university confirmed that the building has a carbon dioxide system but said the footage’s low quality and lack of identifying characteristics prevent officials from confirming its location. “The Meat Science & Animal Biologics Discovery building opened in 2020 as a state-of-the-art facility where UW–Madison students — the next generation of leaders in the meat industry — learn about the safe and humane handling of animals and food products,” Director of Public Affairs Gillian Drummond said in a written statement. The USDA-inspected facility uses commercial-grade equipment for animal handling and meat processing, the university said. UW–Madison also described carbon dioxide anesthesia as common in the U.S. food-processing industry and said it is used to help reduce stress in pigs raised for food. Blum disputes that characterization. He cited a 2024 trade-publication interview in which UW–Madison meat-science professor Jeff Sindelar described controlled-atmosphere stunning as “a very calm, very relaxing, very humane process.” Blum said he believes the video conflicts with that description, while acknowledging he is not a veterinarian or an expert in animal-stunning methods. UW–Madison police confirmed Friday that they opened a case related to the video. “We are aware of the video, we have a case open, and we are currently evaluating the legitimacy of the video and the claims that are being made,” UW Police Executive Director of Communications Marc Lovicott said. “The actions remain under investigation and we are in contact with the individual.” Police have not said whether Blum could face charges. Blum said he sought legal representation after entering the facility and decided to identify himself publicly rather than release the footage anonymously. His animal-rights group also organized a campus demonstration during the week. Members placed flags and a large banner at the base of Bascom Hill on Tuesday under a registered student-organization reservation. The display was removed later that day. Blum said the campaign is intended to push the university to provide more information about activity inside the facility, which opened in 2020 near student housing and other central campus buildings. “Students deserve transparency about what goes on their campus, on their public campus,” he said.