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This report has been updated.
By Jake Tapper, CNN Chief Washington Correspondent
The U.S. Marshals Service lost two former participants in the federal Witness Security Program “identified as known or suspected terrorists,” according to the public summary of an interim Justice Department Inspector General’s report obtained by CNN.
The Marshals Service has concluded that “one individual was and the other individual was believed to be residing outside of the United States,” according to the summary.
A Justice Department official said in response to follow up questions about the matter by reporters that the pair had left the program years ago and had been accounted for.
It was not clear when or for how long the Marshals Service lost track of them.
The report notes that while in the middle of an audit of the WITSEC program, also referred to as "WitSec," the IG notified the Justice Department of national security vulnerabilities, and the IG’s office “developed the interim report to help ensure that the Department promptly and sufficiently addressed the deficiencies we found.”
After its audit, the IG’s office reported “the department did not definitively know how many known or suspected terrorists were admitted into the WITSEC program,” among other “significant issues concerning national security.”
As of March 2013, the Justice Department was reviewing more than 18,000 Witness Protection Program case files to determine whether more known or suspected terrorists have been admitted to the program, the summary notes. As such, the number of terrorists lost or unaccounted for “may not be complete and may continue to evolve.”
The IG summary said that although the Marshals Service was giving known or suspected terrorists who participated in the WITSEC program and their dependents new names and identity documentation, the Justice Department “was not authorizing the disclosure to the Terrorist Screening Center,” which operates the terrorist watch list that helps provide information to the Transportation Security Administration’s No-Fly and Selectee lists. “Therefore it was possible for known or suspected terrorists to fly on commercial airplanes in or over the United States and evade one of the government’s primary means of identifying and tracking terrorists’ movements and actions,” the summary said.
The IG’s office notified the Justice Department of these problems and in the middle of remedying them, marshals discovered they could not account for the two missing people.
Justice Department officials on Thursday would not say they knew specifically where the two individuals were.
"We know they left the country years ago, they left the program years ago, they have been accounted for. There has been no information provided that they have ever returned to the United States," said a Justice Department official on a conference call with reporters.
A Justice Department official also told CNN that the pair "completed their obligations to the U.S. government by cooperating against terrorists," were not fugitives, and that "for obvious reasons, we cannot comment on the exact location of any current or former participant in the WitSec program."
President Barack Obama did not comment when asked about the matter at a news conference.
The Marshals Service concluded that “one individual was and the other individual was believed to be residing outside of the United States.”
The Justice Department told the IG that the two were in the program because they had cooperated with United States national security officials and their investigations.
Different government law enforcement agencies not sharing information and intelligence with others has long plagued the U.S. government and national security apparatus, as seen before the 9/11 attacks and as recently as the Boston Marathon bombing. In this case, the IG’s office concluded that the two Justice Department bodies primarily responsible for managing the WITSEC program – the Marshals Service and the Criminal Division’s Office of Enforcement Operations – “did not involve national security stakeholders when admitting and monitoring known or suspected terrorists into the WITSEC program.”
The news comes in the middle of a week of bad news for the Obama administration, with revelations that the Justice Department secretly collected months of phone records for reporters and editors at The Associated Press; renewed criticism and accusations of a cover-up over the White House’s response to the Benghazi attack; and revelations that the Internal Revenue Service targeted conservative groups applying for tax-exempt status.