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The FBI will have up and running within two years a database that tracks instances of police use of deadly force, FBI Director James Comey told lawmakers Wednesday at a congressional hearing that reflected the sustained political interest in the Hillary Clinton email investigation.

The database is intended to capture how often police officers kill citizens in the line of duty and to correct a record-keeping gap that Comey said has resulted in uninformed conversations, based on anecdotes and not facts, about use of force. Demands for more complete records have grown in the past two years amid a series of high-profile deaths at the hands of police officers.

"Everybody gets why it matters," Comey said of the planned database at an oversight hearing of the House Judiciary Committee.

Much of the hearing, though, focused on the FBI's handling of the now-closed investigation into Clinton's use of a private email server as secretary of state.

Republican members of the House Judiciary Committee took turns criticizing Comey over the investigation of Hillary Clinton's private e-mail server at a hearing Wednesday and the decision not to seek prosecutions

Republican lawmakers demanded to know why the Justice Department had granted immunity to multiple individuals interviewed during the investigation, including Clinton's former chief of staff, and questioned whether someone in a less-powerful position than Clinton would have received the same treatment.

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FBI Director James Comey testifies before the House Oversight and Government Reform Committee hearing on 'Oversight of the State Department', focusing on the FBI's recommendation not to prosecute Democratic presidential candidate Hillary Clinton; on Capitol Hill in Washington, D.C., July 7, 2016. MICHAEL REYNOLDS / EPA

The FBI recommended against prosecution in July and the Justice Department closed the matter.

Comey said the FBI has no plans to re-open the investigation, despite some Republican calls to do so.

Comey again rejected the idea of a double-standard and that political considerations were factors in the case.

"You can call us wrong, but don't call us weasels. We are not weasels," Comey said.

Related: FBI's Comey: Officials Worry About 'Terrorist Diaspora' from Syria, Iraq

Committee Democrats, on the other hand, wanted to know if the FBI was investigating discussions Donald Trump campaign staffers may have had with Russian officials. In response to a number of questions along these lines, Comey said the FBI does not confirm or deny the existence of any investigations.

It was the second time in two days that Comey has faced questions from members of Congress. He is the sole witness as the House Judiciary Committee reviews the FBI's performance in what is likely to be the agency's final oversight hearing this year.

Comey also told the House hearing that the FBI is "spending a lot of time" looking into potential hacking of the U.S. election system.

Related: Why Police Officers Often Aren't Convicted for Using Lethal Force

On Tuesday, Republican senators on the Homeland Security and Governmental Affairs Committee pressed Comey on whether anything could have been done differently to prevent recent acts of extremist violence, such as the Orlando nightclub massacre or the Manhattan bombing. Comey told senators that the FBI is transparent about mistakes, but under questioning from Republicans, he did not agree that anything should have been done differently.