His CIA career included assignments in Africa, Afghanistan and Iraq, but the most perilous posting for Jeffrey Scudder turned out to be a two-year stint in a sleepy office that looks after the agency’s historical files.

It was there that Scudder discovered a stack of articles, hundreds of histories of long-dormant conflicts and operations that he concluded were still being stored in secret years after they should have been shared with the public.

To get them released, Scudder submitted a request under the Freedom of Information Act — a step that any citizen can take, but one that is highly unusual for a CIA employee. Four years later, the CIA has released some of those articles and withheld others. It also has forced Scudder out.

His request set in motion a harrowing sequence. He was confronted by supervisors and accused of mishandling classified information while assembling his FOIA request. His house was raided by the FBI and his family’s computers seized. Stripped of his job and his security clearance, Scudder said he agreed to retire last year after being told that if he refused, he risked losing much of his pension...