Ex-Trump aide pleads guilty, will cooperate in Russia probe

FILE - In this Dec. 11, 2017, file photo, former Trump campaign chairman Paul Manafort arrives at federal court in Washington. In a dramatic escalation of pressure and stakes, special counsel Robert Mueller filed additional criminal charges Feb. 22, 2018, against Manafort and his business associate, Rick Gates. (AP Photo/Susan Walsh, File)

Rick Gates arrives at federal court in Washington, Friday, Feb. 23, 2018. Gates, a former top adviser to President Donald Trump’s campaign is scheduled to plead guilty in the special counsel’s Russia investigation to federal conspiracy and false statements charges. (AP Photo/Susan Walsh)

WASHINGTON — A former senior adviser to President Donald Trump’s election campaign pleaded guilty Friday to federal conspiracy and false-statements charges, switching from defendant to cooperating witness in the special counsel’s probe of Trump’s campaign and Russia’s election interference.