A Secret Service agent testified at a Monday hearing that when another agent placed a thumb drive belonging to Yujing Zhang—the Chinese woman arrested for attempting to breach President Trump’s Mar-a-Lago club—into his computer, the drive “immediately began to install files.” Secret Service agent Samuel Ivanovich described the event as “very out-of-the-ordinary,” according to the Miami Herald. Ongoing analysis of Zhang’s thumb drive remains “inconclusive.” Zhang reportedly had multiple devices in her hotel room—including a “signal detector” to locate hidden cameras, a second cell phone, nine USB drives, and five sim cards. Officials also reportedly found $7,500 in U.S. dollars and $663 in Chinese yuan in her room. Prosecutors are reportedly treating the case as a “national-security matter” with the FBI investigating.

Zhang was arrested in late March after she attempted to breach Mar-a-Lago’s security with malware-infected thumb drives, prosecutors said. Li “Cindy” Yang, the former owner of a day spa chain, reportedly advertised access to Mar-a-Lago events to Chinese clients along with a Chinese man named Charles Lee. Yang reportedly promoted events that were scheduled for the day Zhang was arrested. Zhang allegedly told investigators someone named “Charles” invited her to the club.