President Trump’s nominee to lead the Justice Department’s criminal division told senators Tuesday that he once represented a Russian bank that was alleged to have a Trump Organization connection, but he cast that representation as a routine part of his legal work and forcefully asserted that he would be an independent and fair-minded law enforcement official.

Brian Benczkowski, a veteran Republican lawyer who served as staff director of the Senate Judiciary Committee under Sen. Jeff Sessions (R-Ala.) and helped manage the Justice Department transition for the Trump team, acknowledged that he represented Alfa Bank, a Russian financial institution, earlier this year. The institution was referenced in a dossier containing unproven, and sometimes salacious, allegations about Trump and his advisers and their possible Russian connections, and Slate raised questions about communications between servers for the bank and the Trump Organization.

Benczkowski said he was asked by a partner in his firm, Kirkland & Ellis, to help represent Alfa Bank, which wanted to conduct an internal investigation of the server communications. Benczkowski said he hired and oversaw a digital forensics firm, Stroz Friedberg, to examine computer traffic that came on the bank’s systems in February and March, with an eye on ultimately taking the findings to the FBI and Justice Department.

The representation was first reported by the New York Times.

Benczkowski said the review he oversaw uncovered no link between the Trump Organization and Alfa Bank. He said he had been scheduled to meet with the FBI and the Justice Department to present some findings, but before the meeting occurred, he had begun having conversations about a Justice Department job and told Alfa Bank he could no longer participate in the meeting.

Benczkowski said he was also asked by Viet Dinh, the partner who brought Alfa Bank to the firm, to assess whether Alfa Bank could substantiate a defamation case against BuzzFeed, which published the salacious dossier. The bank’s owners ultimately did file a lawsuit. Benczkowski declined to say what advice he provided.

Investigators probing possible coordination between the Trump campaign and the Kremlin have looked into the allegations contained in the dossier about Alfa Bank but have not found evidence of suspicious activity, according to people familiar with the probe. Benczkowski said he would recuse himself from any matters involving the bank for two years and would permanently step aside from any matters that touched on his work for the institution.

Legislators pressed Benczkowski on his representation of the bank, given his role in the Trump transition and discussions about coming on in a more permanent capacity. He defended working for the institution, saying it was in line with the work he had done throughout his career in the private sector.

Before joining Kirkland & Ellis, Benczkowski had worked as chief of staff for the attorney general and deputy attorney general, chief of staff to the director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, and principal deputy assistant attorney general for legislative affairs.

“I was a lawyer in private practice doing what lawyers in private practice do,” Benczkowski said.

Benczkowski’s confirmation hearing came as the president continued to publicly criticize Benczkowski’s former boss, Sessions, leaving the attorney general’s future in doubt. The president and his attorney general have had a falling out over Sessions’s decision to recuse himself from the probe into whether the Trump campaign coordinated with the Kremlin to influence the 2016 election.

Benczkowski said he had “every confidence” that Sessions had “reviewed the facts, he applied the law and he made the right decision for the department on that basis” in stepping aside from the probe. He also defended special counsel Robert S. Mueller III, who also has come under attack by Trump. Benczkowski said he did not agree that Mueller’s probe was a “witch hunt,” a term the president has used to describe it, and he praised Mueller’s “admirable history of public service.”

“He is someone who is widely understood to be a man of integrity, a man of independence and someone who I believe will conduct his investigation with those characteristics right at the forefront, and I also believe he’ll insist on those same things from the people who work for him,” Benczkowski said.

Benczkowski declined to say whether he would step aside if Trump ordered Mueller’s firing, suggesting he would have to factor into such a decision the “disruption” it would cause the department. The criminal division is responsible for the bulk of the Justice Department’s criminal work, including on violent crime and public corruption, and Benczkowski noted his work was not likely to intersect with Mueller’s.

Devlin Barrett contributed to this report.