The U.S. Air Force and FBI raided several Nevada homes earlier this month as part of an investigation into a website about the secretive Area 51 military base. “This is an open and ongoing law enforcement investigation between the Las Vegas FBI and Air Force [Office of Special Investigations],” a spokesman for the Nellis Air Force Base in Las Vegas was quoted telling the Las Vegas Review-Journal. The nature of the investigation was not immediately clear, but the homes searched belong to a man named Joerg Arnu who runs a website devoted to activities at Area 51, a site that has become the focus of a slew of conspiracy theories about UFOs, alien spacecraft, and the development of shadowy new technologies. The Dreamland Resort website features articles about UFOs and “black projects” at the base, as well as videos from drones flown over the base and satellite images, the Review-Journal reports. Arnu said in a statement that he believes the raids are “meant as a message to silence the Area 51 research community.”