The Mueller investigation was a probe led by former FBI Director Robert Mueller into Russian interference in the 2016 U.S. presidential election. It aimed to determine whether the Trump campaign colluded with Russia and to investigate any related criminal activities. The investigation began in May 2017 and concluded in March 2019. The final report outlined various contacts between the Trump campaign and Russian officials but did not establish a criminal conspiracy. It also examined potential obstruction of justice by President Trump, leading to further discussions about accountability and legal implications.