The United States’ former national security adviser pleaded guilty Friday to making false statements to the Federal Bureau of Investigation, or FBI. Michael Flynn is the first official from President Donald Trump’s administration to plead guilty in an investigation led by Special Counsel Robert Mueller. The special counsel is examining possible ties between Russia and the Trump presidential campaign in 2016. Flynn admitted to lying about his contacts with the Russian ambassador to the United States, Sergey Kislyak, before Trump’s inauguration. Court papers make clear that Flynn knows the identities of members of Trump’s transition team that had detailed knowledge of his outreach to Russia. U.S. District Court Judge Rudolph Contreras said Flynn is cooperating with the investigation.