To be honest, I probably wasn’t their best choice. I had never covered the C.I.A. or the F.B.I.; I’d spent much of my career at The Times covering the medical industry and public health issues. But I told Dave and Ira that I would be willing to review his files and records. So, after traveling to Florida to get permission from Bob’s wife, Christine, I flew down to Dave McGee’s law firm in Pensacola, Fla., where a journalistic fantasy awaited.

Image An undated photo of Robert Levinson. Credit... Christine Levinson, via Associated Press

On a desk in a conference room sat ten cardboard boxes crammed with files that were a mix of Bob’s work for the C.I.A. and for corporate clients. Every folder was a fragment from a little-glimpsed shadow world where information serves as currency and the lines between the “good” guys and the “bad” guys are often blurry. One file recounted, for example, how a big donor to Hillary Clinton’s New York Senate campaign was looking to get his prison time on a fraud charge reduced in exchange for information about the leader of Hezbollah, the Lebanese terror group. In another file, an emissary offered the services of the president of Kazakhstan as an informant for the United States government if the Justice Department unfroze the politician’s Swiss bank account, which was allegedly stuffed with bribes paid to him by multinational companies. Meanwhile, Dave’s paralegal, Sonya Dobbs, had figured out the passwords to Bob’s email accounts and was printing out hundreds of messages, including many from the investigator’s handler at an analytical unit inside the C.I.A.

I had planned to spend two days in Pensacola. When I finally left — nearly a week later — my head was spinning. I had gotten a glimpse into Bob’s life, and it was clear to me that C.I.A. analysts had encouraged him to collect intelligence about Iran, a country about which he knew little. There was nothing to show that they had ordered him to go there or even knew beforehand that he had decided to take that risk. Still, there were tantalizing clues. For example, in a memo written not long before his disappearance on Kish Island, he told his C.I.A. handlers that he planned to meet in Dubai or “on an island nearby” with a source who had information about a corrupt Iranian leader.

I spent months reconstructing Bob’s path to Kish and was stunned and dismayed to learn that many of the people I spoke with hadn’t been contacted by the F.B.I. As a condition of reviewing Bob’s files, I had also promised his wife and Dave not to do anything to jeopardize his safety. I liked to flatter myself by thinking that my reporting about medical products, like a flawed heart device, helped people. Now I felt that one wrong step or one inadvertent remark could bring serious harm to someone.

Government officials continued to insist that Bob had gone to Kish to investigate cigarette counterfeiting. As journalists, we instinctively want to tell the truth. But the tiny circle of people at The Times who knew the truth about Bob agreed that identifying him as a C.I.A. consultant could seal his fate or complicate efforts to free him. As a result, we did not challenge the government’s cover story or report on certain events related to his case about which we became aware, such as a secret 2008 internal C.I.A. investigation that led the ouster of three agency analysts, including Bob’s handler.

By then, an international manhunt for the missing man had begun, and some of those recruited by Bob’s friends or the F.B.I. — a collection of colorful characters that included arms dealers, Russian oligarchs and con men — also entered my life. Some of my editors were also losing patience with my obsession over a story that couldn’t be published; they started suggesting that it might be wise for me to find other outlets for my energies. I began casting around for medical stories — and found an important one.