Secret Service Director Julia Pierson testifies on Capitol Hill in Washington. (Associated Press)
The director of the US Secret Service resigned on Wednesday following a string of lapses by the elite presidential protection branch, including one in which an intruder ran through the front door of the White House.
"Today, Julia Pierson, the Director of the United States Secret Service, offered her resignation, and I accepted it," Homeland Security Secretary Jeh Johnson said in a statement.
Johnson appointed Joseph Clancy to serve as interim acting director until a permanent replacement for Pierson, who only took up her post 18 months ago after a prostitution scandal erupted within the agency.
An independent panel would be named to probe the September 19 incident, which saw homeless US army veteran Omar Gonzalez allegedly jump the White House fence and run into the residence, Johnson said.
Gonzalez pleaded not guilty on Wednesday to three counts including unlawfully entering a restricted building or grounds with a deadly or dangerous weapon.
Outraged US lawmakers grilled Pierson on Tuesday over a series of security breaches, including an incident last month in which an armed security contractor with a criminal record was allowed into an elevator with President Barack Obama when he visited Atlanta, Georgia.