WASHINGTON — A man accused of trying to kill President Barack Obama by firing several shots at the White House from long range must remain in custody to protect the public and the president, a federal judge said Monday.

U.S. Magistrate Judge John Facciola’s order that Oscar Ramiro Ortega-Hernandez be detained without bond was not unexpected given the seriousness of the charge Ortega faces — attempting to assassinate the president. It followed a two-hour hearing in which Ortega’s public defender aggressively questioned an FBI agent about the strength of the government’s case and apparent contradictions in witness statements.