(CNN) The release of the Mueller report was just the beginning. The headlines about special counsel Robert Mueller's investigation this weekend came after months of legal pressure from CNN and others pressing the Justice Department to make more of his work public.

On Saturday, both CNN and BuzzFeed published 274 pages of investigative notes and memos from Mueller's interviews with key witnesses about Russian interference in the 2016 election -- and the Trump campaign's involvement. The documents revealed that President Donald Trump, his family members and his top advisers pushed repeatedly to get access to hacked documents WikiLeaks was releasing throughout 2016.

In one memo, former deputy campaign chairman Rick Gates remembered Trump saying, "Get the emails." Also of note, Mueller had learned that former campaign chairman Paul Manafort had pointed to Ukraine for hacking the Democratic emails , a conspiracy theory that lodged in Trump's mind and became part of what he asked the Ukrainian President for help with in July.

The documents illustrated with new examples the factual conclusions Mueller found about how Trump has welcomed foreign help in elections. And they're only the first slim window into the massive trail of Trump campaign activity Mueller's team followed over two years. Mueller's team ultimately interviewed about 500 witnesses and gathered millions of documents, which he distilled into a dense collection of findings in his final report.

This is how we got the new documents.

The race for public access was on when Mueller finished his work in March.

CNN almost immediately began pinging the Justice Department and other agencies with requests for public access to more documents, citing the federal Freedom of Information Act. In all, I sent the Justice Department, FBI and other agencies almost 60 letters requesting different types of communications, memos and investigative paperwork related to the Mueller investigation, with most of my requests emailed out a day or two after Mueller said he was done.

Through April and May, the federal agencies deflected nearly all of my requests related to Mueller, often saying they needed more time to review the requested documents because it was "unusual circumstances" and would need an unspecified amount of extra time to handle.

Under the Freedom of Information Act, the public has a right to access many records created by the federal government, from emails to calendar entries to other notes, within about a month following a request. But requests for sensitive information or lots of papers can take the government years to fulfill. Transparency groups like Judicial Watch and Citizens for Responsibility and Ethics in Washington sue frequently when they don't receive documents quickly, allowing them to jump to the front of the line for access. These groups, when they win, often make the documents public immediately on their websites, and the FBI and other agencies sometimes follow by posting the records on their websites as well.

News organizations including CNN, The Washington Post and others have worked together and succeeded in getting public access to sealed court records from the Mueller investigation. But most groups waited for Mueller to say he was finished before pushing FOIA issues into court.

Jason Leopold at BuzzFeed News, a reporter who's become known for his aggressive records requests and lawsuits fighting for the release of documents, also filed many Freedom of Information Act requests about Mueller. So had the Electronic Privacy Information Center, a transparency group that was first out of the gate to sue for access to Mueller's records.

It sued under FOIA for the Mueller report and other documents Mueller created the day he announced his investigation was over. BuzzFeed News stepped up with its own set of lawsuits in early May, lumping dozens of Leopold's requests into each suit. One of BuzzFeed's lawsuits asked for a plethora of records that fell into six different categories, one being "all FBI 302s," meaning memos from witness interviews, "maintained/stored/in possession of the FBI" related to the Mueller investigation.

CNN sued on June 4 for access to documents I had requested more than a month earlier : the "FBI memoranda, such as 302s, from any and all of the interviews" of the 500-some witnesses in the Mueller investigation, plus "any and all case files related to" those witnesses. Our lawyers, editors and I had realized we wanted to prioritize what we asked for when we went to court. We had zeroed in on the FBI 302s as our highest priority -- the limited, main set of documents we wanted the federal court's help to make public, and quickly.

Because both CNN and BuzzFeed had specifically asked for the FBI witness memos from the Mueller investigation, CNN's focused lawsuit was eventually combined with BuzzFeed's broader one.

Judge Reggie Walton of the federal court in Washington agreed with our news organizations' legal teams. At a hearing in early October, Walton ruled that the Justice Department should turn over the 302s in monthly chunks to CNN and BuzzFeed.

"Obviously there is a real concern as to whether there is full transparency," Walton had said , shortly after the Electronic Privacy Information Center and BuzzFeed had taken their requests to court this summer. He reiterated his concern about how slow a track the administration was on in making Mueller's documents transparent. "The American public is going to become totally disillusioned," he said at the October hearing, after the Justice Department explained it didn't have the resources to process the recent avalanche of public records requests.

Walton gave the Justice Department its first deadline for November 1. The judge added that the administration must process 500 pages a month of the witness memos, and give CNN and BuzzFeed the public documents on the first of every month.

So the Justice Department overnighted Leopold and me CDs on Friday. My request's FedEx tracking number gave a November 2 delivery -- a day late, and a weekend when Washington was largely distracted by its World Series parade.

Saturday morning, I drove to our lawyers' office in downtown DC, where a mail room employee had been specially waiting for the package's arrival. The handoff was complete

When I got the disc back to CNN's Washington bureau and popped it in a computer, one file held 274 pages containing redacted FBI memos. The memos described some of Mueller's interviews with Gates, former Trump adviser Steve Bannon and former Trump attorney Michael Cohen. Among the documents, the Justice Department also provided the additional handwritten notes and relevant emails. The rest of the 500 pages due to us were withheld for reasons the Freedom of Information Act allows, the Justice Department said.

In less than a month, we're expecting the next CD.

The House of Representatives, in its impeachment investigation, is pursuing some of the same witness records under different law from FOIA. So far, the House has seen witness interview memos for 17 Mueller witnesses, including White House staffers Sean Spicer, Stephen Miller, Sarah Sanders and others. The Justice Department has said in court that it's working on getting another 16 witnesses' memos, including Bannon's and Gates', to the House.

Conceivably, the memos CNN and BuzzFeed receive in the future could shed more light on what other key witnesses, including former national security adviser Michael Flynn and former White House counsel Don McGahn, said during their interviews. A few are already publicly available, like the memo the FBI wrote after interviewing Flynn in January 2017, when he lied.

Of those other 57 Freedom of Information Act requests I made related to the Mueller investigation, only one has come through. It turned up three pages of unnoteworthy emails about Manhattan US Attorney Geoffrey Berman's recusal from his office's investigation into Cohen, which was previously known.

The Justice Department has said it could take years to get us all 44,000 pages of the FBI memos that the judge has ordered it to make public -- and that's only a sliver of the millions of documents from the Mueller investigation.

CORRECTION: This story has been updated to accurately reflect when BuzzFeed News began its lawsuits over Mueller investigation public records. It was in May.