WASHINGTON, D.C. — In mid-July, President Donald Trump gave a primetime speech in which he raised concerns about a disputed FBI report that China had tried to interfere in the 2020 election in an effort to defeat him.

At the heart of his address was a bitter complaint: that some of the bureau’s intelligence officials had purposefully sought to play down the report to undercut his claims about the race.

One day after Trump attacked those officials on TV, calling for their prosecution, Kash Patel, the FBI director, sent a letter to the U.S. attorney’s office in Kansas City ordering that some of them immediately be investigated for obstruction and conspiracy, one of the agents assigned to the case testified Tuesday.

The agent, Bryan Witt, said that even though the inquiry was generally viewed inside his office as a “witch hunt” and that he had concerns it was “political,” it nonetheless moved forward.…