A Navy veteran from Glen Burnie with a top-secret security clearance working as a government contractor has been charged with stealing government property and taking and keeping classified materials, federal prosecutors announced Wednesday.

Harold Martin, 51, was arrested by the FBI in August, prosecutors said. He reportedly worked as a contractor for the National Security Agency.

Investigators searched Martin's home, two sheds and a vehicle in late August, and have been reviewing terabytes of digital information and thousands of pages of documents, authorities wrote in court documents.

Much of the material was marked as classified, an FBI agent wrote in a criminal complaint against Martin.

The alleged breach comes as the intelligence community has tried to clamp down on insider threats. That work intensified after NSA contractor Edward Snowden leaked thousands of internal documents to reporters in 2013.

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White House spokesman Josh Earnest said the charges against Martin serve as a reminder of the importance of protecting national security information.

"This is certainly a situation that the Department of Justice takes seriously, as evidenced by their complaint," he said Wednesday. "This is also a situation that President Obama takes quite seriously."

Authorities did not say where Martin worked, but The New York Times and other news organizations said he was employed by Booz Allen Hamilton — which also hired Snowden — and worked for the NSA.

Booz Allen Hamilton, a major intelligence community contractor, said Wednesday that one of its employees had been arrested, but it did not name Martin.

"When Booz Allen learned of the arrest of one of its employees by the FBI, we immediately reached out to the authorities to offer our total cooperation in their investigation, and we fired the employee," the company said in a filing with the Securities and Exchange Commission.

"We continue to cooperate fully with the government on its investigation into this serious matter."

Rep. C. A. Dutch Ruppersberger, whose district includes NSA headquarters at Fort Meade, said the allegations raise fresh questions about how intelligence contractors are screened.

Ruppersberger was the top Democrat on the House Intelligence Committee at the time of the Snowden leaks.

"We have to make sure our system of vetting private contractors is very secure," he said.

Ruppersberger said the intelligence community has taken steps to tighten security after Snowden, but stopping one among tens of thousands of workers is always going to be difficult.

"These are very difficult situations when you have insiders," he said. "When you have someone who's been through the clearance process and a background investigation, they're very difficult."

Investigators raided Martin's home on a Saturday afternoon in August. Neighbors said they heard bangs they assumed were stun grenades before seeing Martin being led out in handcuffs.

Martin initially denied taking any files, the FBI agent wrote in court papers, but was confronted with specific documents and acknowledged that he had.

"Martin stated that he knew what he had done was wrong and that he should not have done it beacuse he knew it was unauthorized," investigators wrote.

At least six documents seized by investigators were particularly sensitive, the FBI agent wrote, and their disclosure would reveal sources, methods and techniques used by the nation's security agencies. The documents dated from 2014, after Snowden's leaks.

It's not clear precisely what information Martin is suspected of stealing.

Martin was taken into custody in August. The charges against him were unsealed Wednesday. He remains in detention.

In a court filing from September, also made public Wednesday, authorities said they had to wade through the seized records and get Martin's lawyers security clearances before they could move forward with the case.

Federal authorities and Martin's attorneys were trying to reach a deal to avoid having to obtain a grand jury indictment, prosecutors wrote.

A judge agreed to give investigators until March to file an indictment.

Martin is being represented by James Wyda, the federal public defender in Maryland. Wyda said the charges represent only the first step in the process.

"There's no evidence that Hal Martin has betrayed his country," Wyda said. "What we do know is that Hal Martin loves his family and his country. He served this nation honorably in the U.S. Navy, and he has devoted his entire career to protecting his country. We look forward to defending Hal Martin in court."

Martin was commissioned as an officer in the Navy in 1988, according to Defense Department records. He achieved the rank of lieutenant and served aboard the combat support ship USS Seattle in the early 1990s. He was later assigned to a post in Washington.

A LinkedIn profile under Martin's name says he worked at a succession of defense contractors after leaving active duty in 1995. The LinkedIn page describes Martin's most recent work as consulting for the Defense Department and the intelligence community on how to fight battles over computer networks.

Martin is a graduate student in information systems at the University of Maryland, Baltimore County, a school spokeswoman said. His page on the school's site lists interests in cloud computing, robotics, artificial intelligence and computer security.

The search of his home came shortly after a person or group calling itself the Shadow Brokers dumped NSA hacking tools online and said it would auction off more to the highest bidder. The group remained active this past weekend, complaining online that its auction had not drawn enough interest.

Computer security analysts have said that it was unlikely hackers had broken into the NSA to obtain the tools. They say it's more likely that an insider took them, or a mistake by an operative left them exposed online.

The Associated Press contributed to this article.

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