Joe Biden Vows Thorough Investigation into Trump Officials for Border Policy Joe Biden Vows Thorough Investigation into Trump Officials for Border Policy President-Elect Joe Biden said he will ensure there is a thorough investigation by the Justice Department into officials of President Donald Trumps administration who crafted and carried out the Zero Tolerance policy at the United States-Mexico border to deter illegal immigration. During a press conference on January 8, Biden committed to having the Justice Department open an investigation into Trump officials who carried out the Zero Tolerance policy through which adult border crossers entered separate custody from the children they arrived at the southern border with.