In the cases of six Trump associates charged by special counsel Robert Mueller, the thick court files are virtually devoid of any campaign communications with known Russian government officials during the election, an analysis shows.

The lack of such contacts helps explain why the Mueller team of mostly Democrat-aligned prosecutors ended its investigation Friday without charging a Trump-related person in a Russian conspiracy to affect the 2016 presidential election. Attorney General William P. Barr released a summary of Mr. Mueller’s findings Sunday that said the prosecutor had found no evidence of campaign collusion.

Based on 2017 news flashes, this was not the way it was supposed to turn out.

Publicized on Jan. 10, 2017, the Democratic Party opposition research paper told of an “extensive conspiracy” between the Trump campaign and the Kremlin. Christopher Steele’s dossier, based on six Kremlin sources, captivated Washington and fueled collusion charges by Democrats and the liberal media.

A month later, The New York Times reported a blockbuster: The U.S. government possessed a year’s worth of phone records and intercepts showing that “Trump campaign aides had repeated contacts with Russian intelligence.”

Two months later, President Obama’s CIA chief, John O. Brennan, testified before the House Permanent Select Committee on Intelligence that he has “encountered and am aware of information and intelligence that revealed contacts and interactions between Russian officials and U.S. persons involved in the Trump campaign that I was concerned about because of known Russian efforts to suborn such individuals.”

“It raised questions in my mind, again, whether or not the Russians were able to gain the cooperation of those individuals. I don’t know whether or not such collusion — and that’s your term — such collusion existed,” said Mr. Brennan, who has accused President Trump of treason.

Later that year, CNN reported that “U.S. intelligence agencies noticed a spate of curious contacts between Trump campaign associates and suspected Russian intelligence.”

On Friday, Mr. Mueller officially ended his nearly two-year investigation without charging collusion and by informing the Justice Department that he recommended no further indictments. The cases against six people related to the campaign involve making false statements to authorities, tax evasion, bank fraud, campaign finance violations, unlawful lobbying and witness tampering.

Mr. Mueller has conveyed two indictments against a number of Russian operatives who did the computer hacking and established social media fake recounts in an effort to help Mr. Trump and hurt Democratic candidate Hillary Clinton. There is no charge that any American knowingly took part.

Mr. Mueller issued “speaking indictments” — documents that don’t just list charges but also provide a narrative surrounding the crimes. He also filed motions and sentencing memos.

The Washington Times found only one reference to a contact with a known Russian government official. It involved former Trump attorney Michael Cohen and an attempted hotel deal.

The six cases:

⦁ George Papadopoulos. The 20-something Trump adviser was supposed to be the gateway to proving collusion.

He was informed by a Russian-connected professor in London in March 2016 that the Kremlin might own thousands of Mrs. Clinton’s emails. It was an apparent reference to the 30,000 emails that the former secretary of state destroyed. Many people speculated at the time that China, Russia or some rogue hacker might have obtained the messages.

Mr. Papadopoulos also spoke with a Russian whom the professor identified as a Russian conduit to the Ministry of Foreign Affairs. The topic: Mr. Papadopoulos’ self-appointed project for a Trump-Kremlin meeting. The meeting never happened.

There is no public evidence that Mr. Papadopoulos acted on the Clinton email gossip. He pleaded guilty to lying to the FBI about when he became an official campaign adviser and was given a two-week jail sentence. On media tours, he said he never communicated with any Russian official, nor was he charged with doing so.

⦁ Paul Manafort. The media also viewed Mr. Manafort as the key to unlocking Russian collusion. CNN reported on contacts Mr. Manafort supposedly had with Russian intelligence.

The Mueller team asserted that Manafort’s longtime office manager and translator in Ukraine, Konstantin Kilimnik, was tied to Russian intelligence. The judge in his case said Mr. Mueller had not presented such evidence. Manafort’s main offense was cheating on federal income taxes by failing to disclose $18 million in income.

Manafort defense counsel Kevin Downing castigated the news media for repeatedly reporting that Manafort communicated with the Russian government and blamed “government leaks” for a “false narrative” to try to gin up momentum for the appointment of a special counsel.

Mr. Downing stated in a court filing, “Despite multiple discovery … request in this regard, the special counsel has not produced any materials to the defense — no tapes, notes, transcripts or any other material evidencing surveillance or intercepts of communicates between Mr. Manafort and Russian intelligence officials, Russian government officials (or any other foreign officials).”

⦁ Rick Gates. A Manafort political consultancy partner and Trump campaign aide, Gates turned state’s evidence and was a key witness at Mr. Manafort’s Virginia trial on tax and bank fraud charges.

Gates pleaded guilty a year ago to helping Mr. Manafort launder overseas money. His sentencing was delayed last month as he continues to cooperate in other investigations.

⦁ Michael Cohen. Mr. Trump’s longtime personal attorney wasn’t part of the official campaign staff. The Mueller team brought a charge of lying to Congress.

The Cohen case file is a rare instance in which a Mueller indictment talks about a Russian government contract. Mr. Cohen sent an email to the Kremlin and later spoke once by phone with a Russian official about building a Trump Tower in Moscow.

Cohen lied by telling Congress that talks ended in January 2016 before the Iowa caucuses when in fact they continued until June. Cohen created the January date in his written testimony, his attorney said.

The prime mover on the Moscow Trump Tower project, though, was not inside the Trump Organization. He was Felix Sater, a Russian-born boyhood friend of Cohen and a real estate developer. Cohen spoke to Mr. Trump about the project three times. Mr. Sater is scheduled to testify this week before the House Permanent Select Committee on Intelligence.

⦁ Retired Lt. Gen. Michael Flynn. He pleaded guilty to lying to FBI agents about his discussions during the transition with Russian Ambassador Sergey Kislyak. The discussions dealt with U.S. sanctions against Russia and other foreign policy issues, and not with the election.

Liberals viewed Flynn as another possible gateway to providing Trump collusion. There was no evidence that he colluded with Russians during the campaign.

⦁ Roger Stone. The combative Republican political consultant is charged with witness tampering and lying to the House intelligence committee about his attempted contacts with WikiLeaks.

U.S. intelligence concluded that the anti-secrecy group received stolen Democratic emails and other documents from Russian intelligence and released them in July, October and November 2016.

Mr. Stone was not officially a part of the campaign but continued providing advice to Mr. Trump, a longtime friend. That summer and fall, he was online and on the phone trying to find out when WikiLeaks would strike again. He bragged that he was in direct contact with WikiLeaks founder Julian Assange, only to recant those statements.

The indictment says a “high ranking” Trump campaign official asked Mr. Stone in October about WikiLeaks’ release schedule. On Sept. 26, 2017, he appeared before the House committee and denied he possessed WikiLeaks-related emails.

The indictment states: “In truth and in fact, Stone had sent and received numerous emails and text messages during the 2016 campaign in which he discussed [WikiLeaks], its head, and its possession of hacked emails. At the time of his false testimony, Stone was still in possession of many of these emails and text messages.”

Mr. Assange said he never communicated with the Trump campaign or Mr. Stone. He said many people, including American journalists, contacted WikiLeaks to find out when to expect the next release.

Mr. Stone, who is set to face trial in U.S. District Court in the District of Columbia, maintains there is no certified proof that WikiLeaks received the documents from Moscow.

Carter Page, a former Trump campaign volunteer, is known to have mingled with Russian officials during his trip to Moscow in July 2016 to deliver a public speech.

The Steele dossier said Mr. Page met with two Vladimir Putin associates who offered him bribes. Mr. Page consistently has called the dossier fiction, and he has denied ever meeting the two Putin associates. The former Navy officer and energy investor was not charged in the Mueller investigation.

As for Mr. Brennan, the former CIA chief predicted that numerous Trump-related indictments were imminent right up until the time Mr. Mueller ended his investigation.

On Jan. 25, he said on MSNBC: “I expect there to be a significant number, and a significant number of names that will be quite familiar to the average American.”

He also said, “I think the shoes that are yet to drop are going to be the ones that are going to be the most profound, and that will hit the people at the top of the organization.”

On March 5, he said: “I wouldn’t be surprised if, for example, this week on Friday, not knowing anything about it, but Friday is the day the grand jury indictments come down and also this Friday is better than next Friday because next Friday is the 15th of March, which is the Ides of March. And I don’t think Robert Mueller will want to have that dramatic flair of the Ides of March when he is going to be delivering what I think are going to be are his indictments, the final indictments as well the report.”

As for the February 2017 New York Times article on “repeated” contacts between the Trump campaign and Russian intelligence, then-FBI Director James B. Comey testified to Congress that the story was wrong and he warned congressional leaders not to believe it.