Maria Butina, the 29-year-old Russian gun rights activist indicted this week for acting as a unregistered foreign agent, was involved with suspected Russian intelligence officials and used sex to gain access to conservative power players, according to a court filing submitted by federal prosecutors on Wednesday. The pretrial detention memo, released ahead of a court hearing, contends that Butina should be denied bail because she “poses a serious risk of flight.” The document supports that claim with explosive new allegations.