WASHINGTON — Hours before she announced the House would investigate whether to impeach President Trump, Speaker Nancy Pelosi received a call from him at her Washington home, ostensibly to talk about gun violence. But he quickly changed the topic to Ukraine.

“He kept saying, ‘The call was perfect. When you see the notes, you’ll see the call was perfect,’” Ms. Pelosi recalled in an interview, sharing for the first time how Mr. Trump previewed a reconstructed transcript showing he had asked Ukraine’s president to investigate a political rival.

“Frankly, I thought, ‘Either he does not know right from wrong, or he doesn’t care,’” she said.

On Wednesday, with Ms. Pelosi sitting in the presiding officer’s chair, gavel in hand, Mr. Trump became the third American president to be impeached. But when the final vote was tallied on charges he abused his power and obstructed Congress, the president was one of two Washington figures to go down in the history books.

The other was Ms. Pelosi.

From the moment in January she ascended to the speakership for the second time — she is the only woman to ever hold the office — Ms. Pelosi has been the maestro of the unruly Democratic orchestra that crescendoed on Wednesday to an impeachment vote she sought mightily to avoid. Like a conductor, she has presided over the process with discipline and at times an iron fist, deciding which notes to hit, when to go fast and when to slow down — and when to allow the musicians to play solo.