The memo is dated January 5, 2012. "To: Interested Parties." "Re: Gabriel Sherman."

Two full years before Sherman published a book about Roger Ailes, this book-length memo made the rounds inside Fox News.

It has all the markings of "opposition research" about a political enemy — which is precisely how Ailes viewed Sherman.

The memo, obtained by CNNMoney from two anonymous sources, is a stunning display of Ailes' campaign-like strategies. It includes, among other things, property records, voter registration information, and a note that the researchers could find no criminal record for Sherman.

A printout from the Westlaw database contains his past and present addresses and details of his mortgage.

Another part of the briefing book, dated January 18, is a 41-page "Internet dredge" of notable tweets by Sherman, blog comments about him, and a New York Times write-up of his wedding.

Still another part, titled "Gabriel Sherman Hit List," is a detailed look at Sherman's reporting and commentary about Republican power brokers, media personalities and Fox News personnel.

The Sherman research totals 400 pages. Most of it is run of the mill: print-outs of Sherman's old articles and tweets. All of it appears to be public information, though some of it would be difficult or time-consuming for the average person to find.

The mere existence of the memo shows how Ailes' allies went to extreme lengths to investigate the reporter.

Related: Fox News staff feared Roger Ailes was monitoring them

"We always wondered why Ailes was so obsessed and paranoid about Gabe's book," a former Fox News reporter told CNNMoney.

In the wake of the sexual harassment scandal that ensnared Ailes this summer and led to his resignation, the reporter said, "maybe we know why."

Ailes has denied the harassment allegations that have been leveled against him.

Sherman's book, "The Loudest Voice in the Room," included on-the-record accounts of Ailes in the early 1980s telling a prospective employee, "If you agree to have sex with me whenever I want, I will add an extra hundred dollars a week," and making flirtatious and suggestive comments to another woman.

But it did not unearth the bombshell allegations of sexual harassment that were made in ex-anchor Gretchen Carlson's lawsuit last month.

Sherman has led the way with followup coverage, including a story about the so-called "black ops" consultants whom Ailes retained for private investigations and "campaigns against enemies."

Several of these consultants, known as "friends of Roger" inside the building, have left the network this summer.

The consultants may have been involved in combing through Sherman's past. But it is unclear who actually did the research work for Ailes.

The two sources who provided CNNMoney copies of the memo -- who insisted on anonymity because they said they still fear retaliation by Ailes -- both said that when they received it, they were told it was from the Fox News public relations department.

Some reporters who cover Fox have long suspected that the P.R. department has kept files on them.

Related: Andrea Tantaros lawsuit puts Fox News P.R. operation in unflattering spotlight

Shown a portion of the Sherman memo, a former Fox News employee said she hadn't seen it, but saw other memos like it while working there.

She would not say who else was targeted, but said the memos always contained information like voter registration.

Back in 2012, the Fox News public relations department was led by Brian Lewis, a ruthless lieutenant of Ailes'. Lewis and Ailes together plotted ways to rebut Sherman's book. But Ailes also suspected Lewis of sharing information with Sherman, which reportedly contributed to Lewis's firing in July 2013.

Through his lawyer, Lewis declined to comment on Friday.

Lewis' #2 in the department, Irena Briganti, became the P.R. boss in the months before the book was released. She remains in charge of the department now.

Briganti denied any knowledge of the research memo when contacted by CNNMoney on Friday.

"The Fox News PR department was never involved in conducting or executing any opposition research against Gabe Sherman," she said in a statement. "It's been widely reported that there was a separate team not associated with PR which conducted extensive operations unbeknownst to anyone whose official job was to deal with the press."

Ailes' attorney, Susan Estrich, did not respond to a request for comment.

The Daily Beast reported in 2014 that news library researchers who worked for Fox's "brain room," ostensibly a part of the newsroom, were tasked with scoping out the backgrounds of reporters.

Two anonymous former researchers "described being tasked with keeping close watch on Sherman, including compiling a dossier of every story he had ever written, and providing transcripts every time he was on television," the Beast reported.

The memo obtained by CNNMoney backs this up. The "hit list" section quotes various writings, TV appearances and statements by Sherman, highlighting some key parts in bold. There is a particular focus on Sherman's comments about conservative figures like Matt Drudge and Ailes' boss Rupert Murdoch.

Some of the content in the "Internet dredge" section is downright comical. Page 5, labeled "Greatest Hits from Internet Dredge," quotes a blog commenter making fun of Sherman's marathon running times. It highlights a tweet from Sherman to another user, saying "my wife is very forgiving," and asks in bold, "...Forgiving of What?"

But it also foreshadows lines of attack against Sherman's book. The "Internet dredge" included blog commenters who accused the writer of being "left wing" and "pathetic."

Whether the Sherman memo was produced by P.R. people, Ailes' personal consultants, or others, the information was used to frame Sherman as an adversary of Ailes.

Some of the information contained in the memo subsequently showed up on Conservapedia, a right-wing version of Wikipedia. Anti-Sherman stories also appeared on Breitbart News in 2012 and 2013.

Sherman's book was published in January 2014. The publisher recently re-issued the e-book edition with a new cover reflecting the Carlson lawsuit.

Sherman told CNNMoney he had heard about possible "oppo research" against him and had ample reasons to believe it existed, but has never seen it.

When informed of the document's contents and asked to comment, Sherman said, "I don't take it personally. As I report in my book, Ailes was determined to control his story. This appears to be more evidence of that."