NEW: Mueller's office says ex-Trump campaign chief Paul Manafort met with investigators 12 times, where he "lied in multiple ways and on multiple occasions." 
Mueller's office says Manafort remained in contact with a "senior" Trump administration official though February 2018, well after he was indicted, and lied about it. They confirmed his contacts with administration officials by search his electronic documents.
Mueller also says Manafort lied about his interactions with Konstantin Kilimnik, an associate who the FBI has said was connected to Russian intelligence.
Here's the sentencing filing from federal prosecutors in New York, which is brutal. Our @big_cases bot is following the case ->
And here's the sentencing memo from Mueller's office ->
