WATCH: FBI Director Wray faces Larry Nassar’s victims, says ‘I don’t have a good explanation for you’

"I understand it's a long-standing department policy not to comment on decisions, not to prosecute, but robust oversight of the Department of Justice is a core responsibility of this committee,” Senate Judiciary Chairman Dick Durbin said in his opening remarks. “The FBI's handling of Nassar's case is a stain on the bureau.”

"Today, we believe Nassar abused more than 300 athletes before he was brought to justice. As the details of Nassar's crimes emerged, there's been a consistent theme of neglect and inaction by those who are responsible for protecting the athletes," said Durbin.

Durbin added that he's "disappointed" the Justice Department declined to participate in Wednesday's hearing but promised an oversight hearing with them in the fall.

He confronted FBI Director Christopher Wray on his agency’s repeated neglect and mishandling of the Nasser case, stating: “it had to touch you personally, not only in your official capacity but as a parent, to listen to these young women’s stories of what they had been through. And what strikes me here is there doesn’t seem to have ever been a sense of urgency or immediacy in that Indianapolis field office.”

“The July reporting leading to the vain September attempt to change venue on the case to Lansing — which didn’t happen — and then the later report in Los Angeles, and they sat on it," continued Durbin: What am I missing here? This is like a child kidnapping case. This man is on the loose molesting children, and it appears to be getting lost in the paperwork of the agency."

Wray responded: “Needless to say, I share your reactions, I share your bewilderment, I share your outrage … not just as a parent or brother or husband, but as somebody whose introduction to law enforcement was working as an intern in a DA’s office in a unit specifically focusing on these types of crimes. It’s part of what motivated me to pursue a career in law enforcement in the first place.”

On the fumbling of the Nasser case, he said, “I don’t have a good explanation for you. It is utterly jarring to me and totally inconsistent with what we train our people on, and totally inconsistent with what I see from the hundreds of agents who work these cases every day, and that is why that individual has been fired.”

Michael Langeman, a supervisory special agent in the FBI’s Indianapolis office, was fired in the days leading up to Wednesday’s hearing, according to sources who could not be named because they did not have the authority to speak publicly about the case.

Though Langeman was not named in the report, his actions as the special supervisory agent, and his multiple crucial missteps, were described in detail.

The report said Langeman should have known that Nassar’s abuse was probably widespread, yet he failed to investigate the case urgently. He interviewed only one of the three elite gymnasts who gave the USA Gymnastics details of Nassar’s abuse. Langeman also was unable to document that interview or open an investigation properly.

In an interview report he filed with the FBI 17 months after he spoke to that gymnast — McKayla Maroney, who was not named in the report — he included statements she did not make, according to the report.

"They had legal, legitimate evidence of child abuse and did nothing. If they're not going to protect me, I want to know who they are trying to protect?" she said.

"What's even more upsetting to me is that we know that these FBI agents have committed an obvious crime. They falsified my statement, and that is illegal in itself. Yet no recourse has been taken against them," said Maroney.

"The Department of Justice refused to prosecute these individuals. Why?" she said. "Deputy attorney general Lisa Monaco couldn't bring herself to be here today. It's the Department of Justice's job to hold them accountable."

Wray made a promise and commitment to make sure the FBI doesn't just move on from this case and that the FBI remembers it in "heartbreaking detail" and knows "the pain that occurred when our folks failed to do their jobs."

"I'd like to make a promise to the women who appeared here today and to all survivors of abuse," he said. I am not interested in simply addressing this [as] wrong and moving on. It's my commitment to you that my entire senior leadership team and I are going to make damn sure everybody at the FBI remembers what happened here in heartbreaking detail."

He continued: "We need to remember the pain that occurred when our folks failed to do their jobs. We need to study it. We need to learn from it. That is the best way I know to make sure that this devastating tragedy is never repeated."

"After I became FBI director and when I learned there were people at the FBI who had also failed these women," said Wray, "I was heartsick and furious."

"The actions and inaction of the FBI employees detailed in this report are totally unacceptable. They failed to protect young women and girls from abuse."

He added: "The work we do certainly is often complicated and uncertain. We're never going to be perfect, but the kinds of fundamental errors made in this case in 2015 and 2016 should never have happened. Period. As long as I'm FBI director, I'm committed to doing everything in my power to make sure they never happen again."

The Senate hearing is ongoing, with lawmakers on the judiciary committee questioning Wray and Justice Department Inspector General Michael Horowitz.