Something seemed amiss with the brownstone at 377 Union Street in Carroll Gardens, Brooklyn.

After it sold for nearly $3 million in cash in 2012, the gorgeous four-story townhouse in one of Brooklyn’s prettiest neighborhoods proceeded to become an eyesore and a nuisance. Renovations dragged on for several years, then stopped. I-beams and cinder blocks cluttered the yard. Windows broke. Neighbors complained that the construction caused their basements to flood. The security alarm would go off in the middle of the night for an hour at a time.

“The speed of the transaction was strange, and then the length of the renovation was strange,” said William Jeanes, a retired city worker who lives a few doors down.

The absentee owners broke a cardinal rule of brownstone Brooklyn: There is a ginkgo tree near the house, and in the fall, ginkgos drop fleshy, rotten-scented fruits. The owners were the only ones on their block who did not sweep their ginkgo fruit off the sidewalk.

On Monday, federal prosecutors linked the house to something more than a local annoyance: It was, they charged, a mechanism through which Paul Manafort, the president’s former campaign chairman, laundered millions in unreported income from lobbying work on behalf of pro-Russian politicians in Ukraine.