Secret Service Director Julia Pierson testifies before the House Oversight and Government Reform Committee about the White House perimeter breach during a hearing on Tuesday. Pierson stepped down from her position on Wednesday. Chip Somodevilla/Getty Images hide caption

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This 2009 photo provided by Jerry Murphy shows Omar Gonzalez, who was married to Murphy's mother, Samantha, until they divorced in 2012. Authorities have identified Gonzalez as the man who got into the White House after scaling a fence on Sept. 19. AP hide caption

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Members of the U.S. Secret Service's Counter Assault Team, known in the agency as CAT, are seen before boarding helicopters at a landing zone in Rijksmuseum in Amsterdam, Netherlands, on Monday. Pablo Martinez Monsivais/AP hide caption

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Mark Sullivan, Director of the United States Secret Service, at a hearing of the Senate Homeland Security and Government Affairs Committee in May of 2012. Brendan Smialowski /AFP/Getty Images hide caption

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Homeland Security Secretary Janet Napolitano as she testified this morning before the Senate Judiciary Committee. Mark Wilson/Getty Images hide caption

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