11/1/2016 - Millian was under investigation by the FBI for possible involvement in a program to recruit Americans as Russian spies.Source
34.2. Relationship with Trump
9/8/2016 - “After inquiries from The Daily Beast, the reference to Trump in his biography was scrubbed”, Article also describes Millian meeting Michael Cohen. Source
1/19/2017 - Sergei Millian claimed he helped Trump “Study the Moscow Market” Source
34.3. Relationship to Russia
1/19/2017 – Millian is a Russian Businessman (covered in other sources well enough). Source
35.4. Relationship to Trump Dossier
10/22/2013 - Millian posted a photo of the Ritz in Moscow and checked in on Facebook. Source
1/30/2017 – Millian is the source of the most salacious allegations in the uncorroborated dossier about Trump and the Russians is a onetime Russian government translator, according to a person familiar with the raw intelligence provided to the FBI. Source
3/29/2017 - The allegations by Millian — whose role was first reported by the Wall Street Journal and has been confirmed by The Washington Post — were central to the dossier compiled by the former spy, Christopher Steele. Source
3/31/2017 - In an interview Millian doesn’t want to comment on being contacted by FBI but denies any he is a source for the Dossier. Source (Source is a bit unknown, would like verification but I doubt full interview is made up)