In its last fiscal year, which ended in March, Booz Allen earned $3.9 billion — about three quarters of its total revenue — from its defense and intelligence business. Once its work for other parts of the government is factored in, Booz Allen’s government contracting accounted for 97 percent of its revenue.

But as the two thefts have made clear, employing large numbers of contractors brings security risks, though experts point out that there have been many leaks in recent years that came from government employees, as well.

Booz Allen weathered the Snowden leaks, and it was cleared of any wrongdoing by the Air Force. It has so far had little to say about the Martin case, issuing a brief statement on Wednesday saying it had fired Mr. Martin and was cooperating with the investigation.

Unlike Mr. Snowden, some officials have said, Mr. Martin does not appear to have leaked any of the information he is suspected of stealing, which is believed to be highly classified computer code.

But the problem for Booz Allen is that at least some of the documents alleged to have been found in Mr. Martin’s possession date to 2014. That would call into question the effectiveness of reforms aimed at safeguarding the nation’s secrets announced in the wake of the Snowden affair.

“We have been and will continue to assess the proper role of contract employees in the intelligence community, many of whom play a vital role,” said Representative Adam B. Schiff of California, the ranking Democrat on the House Intelligence Committee. “We must be careful not to overcorrect or to draw the wrong lessons. This issue is fundamentally about preventing and detecting insider threats, both from contractors like Edward Snowden and this individual, and from government employees.”

The leak in 2013 of the materials stolen by Mr. Snowden prompted calls from Sen. Dianne Feinstein of California, then the Democratic chairwoman of the Senate Intelligence Committee, for contractors like Booz Allen to lose their access to highly sensitive intelligence. The Obama administration, meanwhile, tightened security measures at intelligence agencies, and slashed the number of employees with access to classified information by 17 percent.