FBI director Kash Patel has been grilled by the US Senate for nearly five hours over his management of the agency, including the ousting of experienced agents.
Mr Patel's time at the FBI has been marred by his firing of workers with little explanation.
Appearing before the Senate Judiciary Committee, Mr Patel defended his tenure.
Mr Patel defended FBI investigators who worked on the Epstein files release, as part of the Congress-backed Epstein Files Transparency Act.
Survivors of the sex offender said the FBI failed to investigate Jeffrey Epstein in 1996 when the agency was told of the first allegations.
More than 30 of Epstein's victims have now brought forward a lawsuit against the FBI, despite attempts by the Trump administration to dismiss the case.
Mr Patel told the hearing that the FBI had complied with the Transparency Act and "produced three and a half million pages of documents for the first time ever".
One of the stranger moments was when Mr Patel confirmed the FBI had quietly lifted restrictions on hiring applicants who were victims of bestiality in their childhood.
Mr Patel denied the changes reflected a lowering of work standards and said these were designed to prevent victims who had been forced to engage in that conduct from being automatically disqualified.
The questioning spanned partisan lines, with Republican senator John Kennedy of Louisiana grilling Mr Patel about the rationale for a change the FBI director said subordinates proposed to him.
Mr Patel later added that previous regulations disqualified "any individual who participated on either side of it".
Connecticut Democrat Richard Blumenthal pressed Mr Patel.