Financial analysts for the F.B.I. and the Internal Revenue Service testified that Mr. Manafort transferred more than $15 million from those accounts to pay for landscaping, clothing, rugs, home renovations and entertainment systems. In 2012 alone, he wired enough money from the hidden accounts to purchase a loft in SoHo, a brownstone in Brooklyn and a residence in Arlington, Va., they said. Mr. Manafort also disguised some of his income as loans to avoid taxes, witnesses testified.