Rader was arrested while driving near his home in Park City shortly after noon on February 25, 2005. An officer asked, "Mr. Rader, do you know why you're going downtown?"; Rader replied, "Oh, I have suspicions why." Wichita police, the Kansas Bureau of Investigation, the FBI, and Bureau of Alcohol, Tobacco, Firearms and Explosives agents searched Rader's home and vehicle, seizing evidence including computer equipment, a pair of black pantyhose retrieved from a shed, and a cylindrical container. The church he attended, his office at City Hall, and the main branch of the Park City library were also searched. At a press conference the next morning, Wichita Police Chief Norman Williams announced, "the bottom line: BTK is arrested."
On February 28, 2005, Rader was charged with 10 counts of first degree murder. Soon after his arrest, the Associated Press cited an anonymous source alleging Rader had confessed to other murders in addition to those with which he had been connected; the Sedgwick County district attorney denied this but refused to say whether Rader made any confessions or if investigators were looking into Rader's possible involvement in more unsolved killings. On March 5, news sources claimed to have verified by multiple sources that Rader had confessed to the 10 murders he was charged with, but no other ones.