(In this January 25 story corrects paragraph four to say number of individuals is 34, not 35)

FILE PHOTO: Michael Cohen, U.S. President Donald Trump's former personal attorney, exits the United States Courthouse after sentencing at the Manhattan borough of New York City, New York, U.S., Dec. 12, 2018. REUTERS/Brendan McDermid/File Photo

(Reuters) - U.S. President Donald Trump’s long-time ally and campaign adviser Roger Stone was arrested on Friday on seven charges of obstruction, lying and witness tampering as part of the U.S. Special Counsel’s Office Russia investigation.

Stone is one of dozens of people caught up in a long-running investigation of Russian meddling in the 2016 U.S. presidential election and possible collusion between the Kremlin and the Trump campaign, and is the latest Trump associate to be charged.

Trump denies any collusion and has long denounced the investigation led by Special Counsel Robert Mueller as a “witch hunt.” Moscow has denied it interfered in the election.

Here is a list of 34 individuals and three companies who have pleaded guilty, been indicted or otherwise swept up in the inquiry, which has clouded Trump’s presidency and has recently intensified.

MICHAEL COHEN

Trump’s former personal lawyer was sentenced in December to three years in prison for crimes including orchestrating hush-money payments to women in violation of campaign laws before the 2016 election. He promised to keep cooperating with the U.S. government against his former boss.

Trump directed the hush payments to the two women shortly before the election and knew that doing so was wrong, Cohen said in a television interview.

Cohen pleaded guilty on Nov. 29 to lying to Congress about a Trump Organization skyscraper project in Moscow.

Cohen once said he would “take a bullet” for Trump, who called him a “rat” in a tweet in December.

MICHAEL FLYNN

Flynn pleaded guilty in December 2017 to lying to the FBI about his contacts with Russia during Trump’s presidential transition and agreed to cooperate with Mueller.

He was Trump’s national security adviser for less than a month in early 2017. He resigned after it emerged he had misled Vice President Mike Pence and the FBI about his dealings with the then-Russian ambassador to the United States, Sergey Kislyak.

Flynn knew better than to lie to the FBI and does not deserve sentencing leniency, U.S. prosecutors said on Friday. His sentencing is pending.

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PAUL MANAFORT

Trump’s former campaign chairman agreed to cooperate with Mueller in a plea deal announced in September. He was due in court on Friday to respond to U.S. prosecutors’ accusation that he breached his deal by lying to investigators.

Manafort in September pleaded guilty to conspiracy against the United States and agreed to cooperate with Mueller.

He was convicted in August in a separate case in Virginia of bank and tax fraud.

RICK GATES

A former deputy Trump campaign chairman, Gates pleaded guilty in February 2018 to conspiracy against the United States and lying to investigators. He agreed to cooperate with Mueller and testified against Manafort, his former business partner.

KONSTANTIN KILIMNIK

A Manafort aide in Ukraine and a political operative with alleged ties to Russian intelligence, Kilimnik was charged in June with tampering with witnesses about their past lobbying for Ukraine’s former pro-Russian government.

GEORGE PAPADOPOULOS

The former Trump campaign adviser was sentenced in September to 14 days in prison after pleading guilty in October 2017 to lying to the FBI about his contacts with Russian officials, including a professor who told him the Russians had “dirt” on Trump’s Democratic presidential rival Hillary Clinton.

SAMUEL PATTEN

Patten, an American business partner of a Russian national accused by Mueller’s office of ties to Russian intelligence, pleaded guilty in August 2018 to unregistered lobbying for a pro-Kremlin political party in Ukraine. He agreed to cooperate with investigators.

RICHARD PINEDO

Pinedo was not involved with the Trump campaign but in February he pleaded guilty to identity fraud in a case related to the Mueller investigation for helping Russian conspirators launder money, purchase Facebook ads and pay for supplies.

He was sentenced in October 2018 to a year of incarceration and allowed to serve half of it at home.

RUSSIAN OFFICERS

Twelve Russian intelligence officers were indicted by a federal grand jury on July 13, accused of hacking Democratic Party computer networks in 2016.

RUSSIAN NATIONALS, COMPANIES

Thirteen Russians and three Russian companies were indicted in Mueller’s investigation in February 2018, accused of tampering in the 2016 election to support Trump. The companies included the Internet Research Agency, known for its “trolling” on social media, Concord Management and Consulting and Concord Catering.

ROGER STONE

The longtime Trump ally and presidential campaign adviser was arrested on Friday and charged with seven counts of obstruction, witness tampering and making false statements.

Stone, 66, has faced scrutiny for his support for Trump during the 2016 presidential campaign, when he implied he had access to information obtained by hackers that could embarrass Democrats, including Trump’s rival for the White House, Hillary Clinton.

A grand jury indictment released by U.S. Special Counsel Robert Mueller’s office said a senior Trump campaign official had spoken with Stone about the damaging information.

U.S. prosecutors, in the court filing, accused Stone of lying to Congress about his public statements and communications with others suggesting he may have had advance knowledge of plans by Wikileaks to release hacked emails and obstructing Congress’ work.

They also accused him of trying to interfere with a witness, who was a radio host who Stone had known for more than 10 years and matched the profile of Randy Credico.

Stone has previously denied any wrongdoing. Grant Smith, his lawyer, did not immediately respond to a request for comment.

ALEX VAN DER ZWAAN

A lawyer who once worked closely with Manafort and Gates, Van der Zwaan pleaded guilty in February to lying to Mueller’s investigators about contacts with a Trump campaign official. He was sentenced in April to 30 days in prison and fined $20,000.