The intelligence officer who filed a whistle-blower complaint about President Trump’s interactions with the leader of Ukraine raised alarms not only about what the two men said in a phone call, but also about how the White House handled records of the conversation, according to two people briefed on the complaint.

The whistle-blower, moreover, identified multiple White House officials as witnesses to potential presidential misconduct who could corroborate the complaint, the people said — adding that the inspector general for the intelligence community, Michael Atkinson, interviewed witnesses…

The second concern Mr. Atkinson identified, according to the Justice Department memo, was that Mr. Trump’s potential misconduct might expose him “to serious national security and counterintelligence risks.”

Mr. Engel did not elaborate, and it was not clear whether he was suggesting that Mr. Trump would be subject to extortion if foreign officials threatened to expose his purported misconduct or he was referring to some other risk.