Republicans Step Up Attacks on F.B.I. as It Investigates Trump

When George Piro learned that some of his former colleagues were spreading unfounded rumors about him, he was stunned.

Mr. Piro, 55, was a highly decorated agent in the F.B.I. During his 23-year career, he earned a national intelligence medal for the months he spent interrogating Saddam Hussein, supervised several high-profile shooting investigations and consistently earned reviews that were among the highest for agents who ran field offices.

Now, he stood accused of misconduct by a group of former agents who had been placed on leave and called themselves “the...