House Oversight Committee leaders said at the end of a hearing on the Secret Service's mishandling of security incidents at the White House that an independent investigation was needed beyond an internal review.

"An internal investigation by the Secret Service is not sufficient," House Oversight Committee Chairman Darrell Issa (R-Calif.) said as he closed the public hearing.

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"The jury is still out" on Secret Service Director Julia Pierson's leadership, said the panel's top Democrat, Rep. Elijah Cummings (Md.).

Pierson testified before the House Oversight Committee on Tuesday in a hearing that lasted three and a half hours.

Issa and Cummings plan to send a letter to Homeland Security Secretary Jeh Johnson requesting that an independent panel of experts review Secret Service procedures.

Pierson fielded tough questions from lawmakers who suggested there are signs that the Secret Service has sought to hide the seriousness of White House breaches.

Del. Eleanor Holmes Norton (D-D.C.) said revelations that ran counter to what the agency initially told the public about the capture of an accused fence-jumper last week were “troubling.”

Rep. Stephen Lynch (D-Mass.) accused Pierson of a cover-up, saying, "I wish to God you protected the White House the way you're protecting your reputation."

The Secret Service director also met with lawmakers after the public hearing in a closed session to provide classified information about its White House security procedures.

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