For journalists, filing a Freedom of Information Act (FOIA) can be a roll of the dice. Bureaucratic delays are standard for even the most benign FOIA requests. Sometimes, persistence results in flat-out rejection.

That was the outcome of a FOIA request I filed on behalf of 60 Minutes as we reported "The Russian Hack," our look this week at Russian interference in 2016 presidential and congressional races. Prosecutors working for Special Counsel Robert Mueller laid out their case in an extraordinarily detailed indictment of Russian intelligence agents.

Buried deep within the indictment is a reference to an unnamed candidate for Congress who prosecutors say requested stolen materials from a hacker who was reported at the time to be connected to the Kremlin's intelligence services. We wanted to identify this mystery Congressional candidate.

The prosecutors wrote, "On or about August 15, 2016, the Conspirators, posing as Guccifer 2.0, received a request for stolen documents from a candidate for the U.S. Congress. The Conspirators responded using the Guccifer 2.0 persona and sent the candidate stolen documents related to the candidate's opponent."

First, some background: In 2018, the United States Department of Justice (DOJ) announced the indictment of 12 Russian military intelligence officers as a result of Special Counsel Robert Mueller's investigation into Russian interference in the 2016 presidential election. The 29-page indictment described Russia's foreign influence operation in granular detail. The indictment described a classic "hack and dump" campaign conducted by teams of cyber warriors from Russia's notorious military intelligence agency, the GRU. Some of the Russian defendants were charged in the indictment for using a variety of techniques to hack into and steal proprietary documents from computers inside the Democratic National Committee (DNC) and the Democratic Congressional Campaign Committee (DCCC). The DOJ indictment says another Russian military hacker team was tasked to disseminate the documents by using a fictional online persona they created called Guccifer 2.0.

In the summer before the 2016 election, it was widely suspected that the Democratic Party organizations had been hacked by Russian intelligence agents, thanks to reporting by The Washington Post among others. But that didn't stop American political operatives and members of both the mainstream and partisan press from contacting Guccifer 2.0 directly and asking for the stolen material. The indictment alludes to one Republican political strategist in Florida named Aaron Nevins, who used Twitter to send Guccifer 2.0 this direct message: "Feel free to send any Florida-related material." A week later, as Nevins recounted to The Wall Street Journal, his Dropbox account was stuffed with over 2 gigabytes of documents stolen from the DNC and DCCC. Nevins was amazed and – wittingly or not – began conversing with the Russian agents (posing as Guccifer 2.0) – explaining to them the strategic value of the stolen material.

Nevins realized he was playing with fire, but nonetheless soon began releasing the stolen documents on his blog, "Hello Florida," and farming more out to other blogs and mainstream reporters. The First Amendment was being bent to the breaking point.

But there was an equally remarkable story buried on page 16 of the indictment, one that seems to me to require more transparency on the part of the government. The prosecutors wrote, "On or about August 15, 2016, the Conspirators, posing as Guccifer 2.0, received a request for stolen documents from a candidate for the U.S. Congress. The Conspirators responded using the Guccifer 2.0 persona and sent the candidate stolen documents related to the candidate's opponent."

After spending weeks unsuccessfully trying to find out the identity of the mystery congressional candidate, 60 Minutes filed a FOIA request with the FBI and the Department of Justice. We wrote:

"While it is unlikely the 12 GRU agents indicted will be brought to trial, we believe the identity of a candidate for the U.S. Congress specifically asking for and receiving stolen Intellectual Property from the Democratic Congressional Campaign Committee... is clearly in the public interest."

After several back-and-forth exchanges between 60 Minutes and the FBI and DOJ FOIA teams, we received our final answer on August 20, 2019, from the DOJ:

"The records on third party individuals you requested are categorically denied…. The records are exempt from disclosure as the processing of any such third party records would constitute an unwarranted invasion of personal privacy. Therefore, your request is closed."

After our FOIA request was denied, 60 Minutes correspondent Bill Whitaker repeatedly questioned John Demers, the assistant attorney general for national security, about it in an interview this month.

There are other mysteries in the GRU indictment and the larger Mueller report, such as the identification of the two Florida counties where elections systems were allegedly penetrated by the Russian agents. But the fact that someone who could be sitting in the United States Congress today, or may be considering running once again for Congress in 2020, with the possible help of stolen information, is, to me, "need to know" information.