(CNN) There is a web of connections between the Trump campaign, the anti-secrecy website WikiLeaks and the public disclosures it injected into the presidential campaign. Federal investigators are examining some of these relationships and whether any of them were part of an effort to coordinate with Russia's election-meddling efforts.

On Monday, it was revealed that Donald Trump Jr. exchanged some private messages on Twitter with WikiLeaks during the 2016 presidential campaign. The news was first reported by The Atlantic and later confirmed by Trump Jr., who posted screenshots of the messages.

A source familiar with the matter told CNN that Congress has known about these messages for a while and they came up during Trump Jr.'s closed-door testimony in September.

The messages show that WikiLeaks reached out fairly often to Trump Jr., who is only known to have replied on two occasions. Trump Jr.'s final response to WikiLeaks was in October 2016, though the WikiLeaks account continued its outreach until July 2017, according to the messages he released.

That being said, nothing happens in a vacuum, and while these messages were exchanged, WikiLeaks was busy releasing hacked materials. And all the while, Russian President Vladimir Putin was directing an operation to interfere in the US election, according to the US intelligence community.

Here is a timeline with what we know about Trump Jr.'s exchanges with WikiLeaks, the role WikiLeaks played, relevant public statements from the Trump campaign, and much more.

July 2015 -- Russian hackers breach DNC systems

Hackers working for Russian intelligence services "gained access to" the Democratic National Committee's computer networks as part of the Kremlin's campaign to interfere in the 2016 presidential race, according to the US intelligence community assessment that was published after the election.

March 2016 -- Another group of Russian hackers breach DNC systems

Another group of Russian hackers -- separate from the group that hacked the DNC in 2015 -- breached the DNC's computer systems, according to a US intelligence report published after the election. The US intelligence community says Russian intelligence related stolen materials from the DNC to WikiLeaks for public release.

CNN reported this year that Russia gave WikiLeaks the emails through an intermediary.

March 19, 2016 -- Russian hackers gain access to Podesta's emails

Russian hackers gained access to Clinton campaign chairman John Podesta's personal Gmail account by sending a phishing email. The US intelligence community determined in early 2017 that Russian intelligence later gave WikiLeaks hacked emails from Democratic "political figures," an oblique reference to Podesta. CNN reported this year that Russia gave WikiLeaks the emails through an intermediary.

April 26, 2016 -- Papadopoulos learns that Russians have Clinton emails

Trump campaign adviser George Papadopoulos has breakfast in London with a professor who says he has just returned from meetings in Moscow with high-level Russian officials who claim to have "dirt" on Hillary Clinton and "thousands" of her emails, according to court filings

June 2016 -- Cambridge Analytica CEO emails WikiLeaks

Cambridge Analytica, a data analytics firm, started working for Trump over the summer of 2016. Some members of Cambridge Analytica staff were incorporated in the Trump campaign's data operation team. Alexander Nix, the chief executive of data firm Cambridge Analytica, emailed WikiLeaks founder Julian Assange seeking access to emails from Clinton's private server so he could turn them into a searchable database for the campaign or a pro-Trump political action committee. There is no evidence that Clinton's deleted emails were ever hacked or that WikiLeaks ever had possession of them.

June 9, 2016 -- The Trump Tower meeting

Donald Trump Jr., his brother-in-law Jared Kushner, and Trump's then-campaign chairman Paul Manafort attended a private meeting at Trump Tower with a Russian lawyer and others. The meeting was arranged after Trump Jr. was promised damaging information on Hillary Clinton.

June 15, 2016 -- DNC claims it was hacked by Russian intelligence

The DNC and CrowdStrike, a cybersecurity firm it hired to investigate the breaches, revealed publicly for the first time that its servers were penetrated. CrowdStrike said it "identified two sophisticated adversaries on the network" that were associated with Russian intelligence services.

Trump dismissed the notion that Russia was behind the hacks, saying "we believe it was the DNC that did the 'hacking' as a way to distract from the many issues facing their deeply flawed candidate and failed party leader. Too bad the DNC doesn't hack Hillary Clinton's 33,000 missing emails."

July 22, 2016 -- WikiLeaks releases about 20,000 hacked DNC emails

WikiLeaks posted on its website nearly 20,000 emails that were stolen from the DNC servers. Many of the emails were sent by senior DNC officials. Some of the emails suggested that the DNC favored Clinton over Sen. Bernie Sanders in the primaries, leading to allegations that the primary was rigged.

July 25, 2016 -- Trump says it's a 'joke' that Russia hacked the DNC

Trump weighed in on the DNC leaks, saying on Twitter : "The new joke in town is that Russia leaked the disastrous DNC e-mails, which should never have been written (stupid), because Putin likes me."

July 26, 2016 -- NYT reports that the US believes Russia hacked the DNC

The New York Times published a report that claimed US intelligence agencies told the White House that they were highly confident that the Russian government was responsible for hacking the DNC. This was the first public report suggesting that the US government agreed with the DNC's assessment.

July 27, 2016 -- Trump publicly asks Russia to hack Clinton's deleted emails

At a news conference , Trump publicly called on the Russian government to hack Clinton's private email server and reveal the deleted emails. Trump's campaign later said his comment was a joke.

"If it is Russia -- which it's probably not, nobody knows who it is -- but if it is Russia, it's really bad for a different reason, because it shows how little respect they have for our country, when they would hack into a major party and get everything," Trump said. "But it would be interesting to see -- I will tell you this -- Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing. I think you will probably be rewarded mightily by our press. Let's see if that happens. That'll be next."

August 8, 2016 -- Roger Stone says he was in touch with Assange

During a speech in Florida , former Trump campaign adviser Roger Stone claimed to be in touch with Assange and predicted upcoming WikiLeaks releases: "I actually have communicated with Assange. I believe the next tranche of his documents pertain to the Clinton Foundation but there's no telling what the October surprise may be." He later clarified that while he was in contact with Assange, it came through an intermediary.

August 14-17, 2016 -- Stone exchanges messages with Russian hackers

Stone exchanged direct Twitter messages with Guccifer 2.0, a self-proclaimed hacker who published stolen materials from the DNC earlier in the summer. (These DNC releases were separate from the DNC emails published by WikiLeaks.) The Twitter messages were about the contents of some of the stolen DNC materials that Guccifer posted online earlier that summer. Stone denies any wrongdoing or collusion.

Months after these Twitter messages, the US intelligence community announced that Guccifer 2.0 was actually run by Russian intelligence operatives as part of the Kremlin's effort to meddle in the election.

August 21, 2016 -- Stone predicts upcoming trouble for Podesta

Without specifically referencing emails, Stone predicts that Podesta will soon be in hot water. "Trust me, it will soon the Podesta's time in the barrel," he tweeted . Stone later claimed that he wasn't talking about the upcoming WikiLeaks releases but was alluding to an expose he was planning on his own.

September 9, 2016 -- Stone exchanges more messages with Russian hackers

Stone exchanged direct Twitter messages with Guccifer 2.0. The emails were about the contents of some publicly released DNC materials. Stone denies any wrongdoing or collusion.

September 16, 2016 -- Stone predicts WikiLeaks will release Clinton emails

Stone says in a radio interview that WikiLeaks will release new Clinton emails. "I expect Julian Assange and the WikiLeaks people to drop a payload of new documents on Hillary on a weekly basis fairly soon. And that, of course, will answer the question of exactly what was erased on that email server."

September 21, 2016 -- WikiLeaks and Trump Jr. exchange private messages on Twitter

WikiLeaks reached out to Don Jr. just before midnight on September 20, 2016, regarding an anti-Trump website that it said was about to launch. WikiLeaks guessed the password and shared it with Trump Jr., who replied, "Off the record I don't know who that is but I'll ask around. Thanks."

September 21, 2016 -- Trump Jr. emails senior campaign officials about WikiLeaks

Trump Jr. emailed a group of senior Trump campaign officials notifying them that WikiLeaks had reached out, according to The Atlantic . The email was sent to Trump's son-in-law Jared Kushner, then-campaign manger Kellyanne Conway, then-campaign CEO Steve Bannon and Brad Parscale, who ran the campaign's data operation. Kushner also forwarded the email to Hope Hicks, the communications aide who is now White House communications director, according to The Atlantic.

October 2, 2016 -- Stone alludes to future WikiLeaks releases

Stone appeared to predict that WikiLeaks would soon post damaging materials about Clinton. He posted: "Wednesday @HillaryClinton is done. #WikiLeaks." Nothing materialized on the date Stone referred to, but two days later, WikiLeaks started releasing Podesta's emails.

October 3, 2016 -- Trump Jr. and WikiLeaks exchange more private messages on Twitter

WikiLeaks sent a link about Clinton criticizing Assange to Trump Jr., asking him to share it. Trump Jr. replies: "Already did that earlier today. It's amazing what she can get away with." In a follow-up message, Trump Jr. asks, "What's behind this Wednesday leak I keep hearing about?" WikiLeaks does not respond to his question, which appears to reference Stone's post from the day earlier about upcoming releases.

October 5, 2016 -- Stone says "payload coming" from WikiLeaks

"Libs thinking Assange will stand down are wishful thinking. Payload coming," Stone tweeted , two days before WikiLeaks began releasing thousands of emailed hacked from Podesta's email account.

October 7, 2016 -- US formally blames Russia for DNC hacks

The US government broke its silence about the DNC hack. The Office of the Director of National Intelligence, which oversees the entire US intelligence community, announced that the Russian government was behind the hacked emails released by WikiLeaks.

"The US Intelligence Community is confident that the Russian Government directed the recent compromises of e-mails from US persons and institutions, including from US political organizations," the statement said, adding that disclosures on WikiLeaks were consistent with Russian methods.

October 7, 2016 -- WikiLeaks begins releasing Podesta emails

Shortly after the announcement blaming Russia for the DNC hacks, WikiLeaks began posting thousands of emails stolen from Podesta's Gmail account. WikiLeaks went on to release new Podesta emails on a near-daily basis, creating waves of negative headlines for the Clinton campaign in the closing weeks of the election. Trump regularly cited the latest Podesta releases during campaign rallies in October and November. The US government later said Russia was responsible for the hacks.

October 10, 2016 -- Trump says "I love WikiLeaks"

At a rally in Pennsylvania, Trump expressed his admiration for the anti-secrecy website that was publishing dirt on his Democratic opponent, saying "This just came out. WikiLeaks! I love WikiLeaks."

October 11, 2016 -- Trump encourages people to read WikiLeaks

Trump tweets about WikiLeaks: "I hope people are looking at the disgraceful behavior of Hillary Clinton as exposed by WikiLeaks. She is unfit to run."

October 11, 2016 -- Trump Jr. speaks at dinner for Russia-friendly organization

Trump Jr. flew to France and spoke at a dinner hosted by the Center of Political and Foreign Affairs, according to the Wall Street Journal . The paper reported that Trump Jr. was paid for the speaking engagement. The think tank was founded by Fabien Baussart. He and his wife, Randa Kassis, hosted the event Trump Jr. attended in Paris. She leads a Moscow-endorsed Syrian opposition group and has met with many senior Russian officials. In December 2016, the think tank nominated Putin for the Nobel Peace Prize.

October 12, 2016 -- WikiLeaks asks Trump Jr. to tweet about their latest releases

WikiLeaks sent a message to Trump Jr., which said: "Hey Donald, great to see your dad talking about our publications. Strongly suggest your dad tweet this link if he mentions us," the message said, along with an obscure domain that likely hosted an archive of the latest WikiLeaks releases. The website is now offline. Trump Jr. did not reply to the message.

October 12, 2016 -- Trump says WikiLeaks isn't getting enough coverage

Trump tweets : "Very little pick-up by the dishonest media of incredible information provided by WikiLeaks. So dishonest! Rigged system!"

October 14, 2016 -- Trump Jr. tweets the link that WikiLeaks gave him

Trump Jr. tweeted out the link that WikiLeaks had sent to him two days earlier via private message. His tweet said : "For those who have the time to read about all the corruption and hypocrisy all the @wikileaks emails are right here"

October 14, 2016 -- Pence denies coordination between Trump campaign and WikiLeaks

Then-Governor Mike Pence, Trump's running mate at the time, gave an interview on Fox News and denied that the Trump campaign was coordinating with WikiLeaks. "WikiLeaks, some have suggested on the left all this bad stuff about Hillary, nothing bad about Trump, that your campaign is in cahoots with WikiLeaks," said the Fox News host. Pence replied, "Nothing could be further from the truth. I think all of us have, you know, have had concerns about WikiLeaks over the years and it's just a reality of American life today, and of life in the wider world." Responding to reports about Trump Jr.'s messages, a Pence spokesman said Monday that he was "never aware of anyone associated with the campaign being in contact with WikiLeaks."

October 21, 2016 -- WikiLeaks asks Trump Jr. to leak his father's tax returns

WikiLeaks asks Don Jr. to leak some of Trump's tax returns to their organization so that they could be released on a friendly platform, according to the private messages released by Trump Jr. WikiLeaks also said that doing this would help discredit people accusing WikiLeaks of being "pro-Trump" and "pro-Russia" source. Trump Jr. does not reply.

November 8, 2016 -- WikiLeaks tells Trump Jr. that Trump should not concede if he loses

WikiLeaks tells Don Jr. that Trump should contest the election and claim that it was rigged if he does not win. This messaging is consistent with the Russian government's posturing around the time of the election, according t o the report released by the US intelligence community in January 2017. The report said: "Before the election, Russian diplomats had publicly denounced the US electoral process and were prepared to publicly call into question the validity of the results. Pro-Kremlin bloggers had prepared a Twitter campaign, #DemocracyRIP, on election night in anticipation of Secretary Clinton's victory, judging from their social media activity."

November 10, 2016 -- Hicks denies any campaign contacts with foreign entities

A Russian diplomat says that some Russians were in touch with Trump's associates during the campaign. In response, Hope Hicks, then a spokeswoman for the Trump transition, issued a blanket denial: "We are not aware of any campaign representatives that were in touch with any foreign entities before yesterday, when Mr. Trump spoke with many world leaders," she told the New York Times . She also told the AP : "It never happened. There was no communication between the campaign and any foreign entity during the campaign."

December 18, 2016 -- Conway denies campaign contacts with Russians

Kellyanne Conway denies any contact between the Trump campaign and Russia in an interview with CBS News' John Dickerson

DICKERSON: All right. We are not going to get any insight into the president-elect's thinking here, but let me try this. Did anyone involved in the Trump campaign have any contact with Russians trying to meddle with the election?

CONWAY: Absolutely not. And I discussed that with the president-elect just last night. Those conversations never happened. I hear people saying it like it's a fact on television. That is just not only inaccurate and false, but it's dangerous.

July 11, 2017 -- WikiLeaks tells Trump Jr. to release his own emails

WikiLeaks sent more private messages to Trump Jr., shortly after news broke that he attended a meeting with Russians at Trump Tower in June 2016. WikiLeaks encouraged Trump Jr. to release all his emails about the meeting. He did not reply to these direct messages, though he did soon release the full email chain that showed he was told that the Russian lawyer who would attend the meeting might have damaging information about Clinton. Assange acknowledged personally writing these messages to Trump Jr., publicly tweeting at the time , "Contacted Trump Jr this morning on why he should publish his emails."

UPDATE: This story has been updated with information about July 11, 2017.