 He was arrested on April 17 and booked as an accomplice to John Wilkes Booth.Within a month of the assassination eight individuals including Spangler had been apprehended and sat in a military courtroom charged with conspiring to "kill and murder" President Lincoln and the three above named high level government officials The crime was done, "maliciously, unlawfully, and traitorously, and in aid of the existing armed rebellion against the United States of America".The military trial began May 9 and lasted until June 30.