Since May of 2017, former FBI director Robert Mueller has led an investigation into Russian interference during the 2016 election.

In 2018, Mueller’s investigation led to its first arrests, indictments and convictions.

In February, 13 Russian nationals and three Russian companies were indicted for the alleged spread of fake news and information warfare.

In June, Mueller indicted 13 more Russians, this time intelligence officers, for allegedly hacking Democratic targets and the Democratic National Committee.

In August, former Trump campaign chairman Paul Manafort was convicted on eight charges involving fraud and tax evasion unrelated to the campaign. Around the same time, President Donald Trump’s former attorney Michael Cohen pleaded guilty to eight federal charges.

The day after the 2018 midterm elections, Trump fired Attorney General Jeff Sessions, who had recused himself from the Russian investigation in 2017. Acting in his stay is Matthew Whitaker, who previously had raised doubts about Mueller’s investigation while serving as Sessions’ chief of staff.

Trump continued to refer to the investigation as a “hoax” and claimed there was “no collusion.” Meanwhile some senators have urged passing of a bill to protect the Mueller investigation until its conclusion, which has no final date.

In late November the president submitted written answers to Mueller, who is reportedly seeking a face-to-face meeting with the president.

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The fifth of our 10 top stories of 2018 will post on Dec. 13.