The House Government Oversight Committee subpoenaed three key figures in the Hillary Clinton email scandal to testify at a hearing Tuesday. Two declined to testify, citing their Fifth Amendment rights. A third refused to show up at all.

One of those who took the Fifth was Paul Combetta, a technician at Platte River Networks, the company that handled Clinton's email system. Combetta is the man who actually deleted Clinton's email archives in March 2015, using the now-notorious BleachBit program. The Justice Department reportedly gave Combetta immunity in its investigation, yet he still refused to talk to Congress.

The other witness who appeared but would not talk was Bill Thornton, an engineer and co-worker of Combetta's at Platte River Networks who worked on the Clinton system. The subpoenaed witness who refused to show up is Bryan Pagliano, the State Department worker who originally created Clinton's private system. Like Combetta, Pagliano has received immunity.

Much of the early part of the hearing involved wrangling over the witnesses' refusal to cooperate. Rep. Jason Chaffetz, the Republican chair of the committee, tried to question Combetta and Thornton only to face the objection of Rep. Elijah Cummings, ranking Democrat on the panel, who argued that it was harassment to force the two to take the Fifth in public.

"This is an absolute abuse of authority," Cummings said.

Rep. Trey Gowdy, a Republican committee member and also an investigator of the Clinton email scandal as chairman of the Benghazi Committee, got into an argument with Democratic Rep. Stephen Lynch over the extent of immunity granted to Combetta and Pagliano. What, exactly, does it cover? Chaffetz jumped in to say that no one knows, because the Justice Department won't tell the committee about the immunity and the witnesses refuse to talk or to provide a copy of their immunity agreements.

Then it came time to question the witnesses. "Mr. Combetta, do you intend to make an opening statement?" said Chaffetz.

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment privilege," Combetta said.

"Mr. Thornton, do you intend to make an opening statement?"

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment constitutional privilege."

"Mr. Combetta, we sent a subpoena to you — we have read that there was an immunity agreement. Mr. Combetta, did you produce your immunity agreement this morning as required under the subpoena?"

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment privilege."

Chaffetz went on to ask Combetta about a couple of emails that suggested trouble with the Clinton system. What did Combetta know about that?

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment privilege."

"One last one here, Mr. Combetta," Chaffetz said. "You're an IT guy who was paid by the Clintons. Generally IT guys don't erase their clients' emails unless they're told to do so. Who told you to delete the emails?"

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment privilege."

The situation took on a comic edge when Chaffetz recognized Cummings to ask questions. Looking at Combetta, Cummings said, "Do you all plan to continue to assert your Fifth Amendment rights — is that your plan?"

Combetta looked briefly confused, and turned to his lawyer for guidance. Then he said, "On advice of counsel, I respectfully refuse to answer and assert my Fifth Amendment privilege." In other words, he took the Fifth when asked if he planned to continue taking the Fifth.

The situation was the same with Thornton, who answered each question with "On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment constitutional privilege."

Before letting Thornton go, Chaffetz had one more question, one which raised a few eyebrows. Even though Thornton was a tech at Platte River Networks who worked on the Clinton system, Chaffetz seemed to suggest the FBI might not have talked to him in its supposedly thorough investigation. "Were you interviewed by the FBI?" Chaffetz asked.

"On advice of counsel, I respectfully decline to answer and assert my Fifth Amendment constitutional privilege," Thornton said.

"You can't answer the question about whether or not you were interviewed by the FBI?"

"On the advice of counsel, I respectfully decline."

Then there was the empty chair, Bryan Pagliano. "Mr. Pagliano has chosen to evade a subpoena duly issued by a committee of the U.S. House of Representatives," Chaffetz said. "This is not an optional activity … when he thumbs his nose at the United States Congress, wastes this committee's time … that is just not acceptable."

It's fair to say that by that point, about half an hour into the hearing, a pattern had developed. The sources who have a unique understanding of how a major part of the Clinton email scandal actually happened had totally shut down. They wouldn't talk. Combetta had also ignored a subpoena for his immunity agreement, which committee investigators haven't seen, don't know the contents of, and can't say with absolute certainty actually exists.

After the hearing, I asked Gowdy for a reaction to what had happened. He was particularly angry about the immunity situation. After all, it seems clear from the partial set of documents the FBI has released that Combetta destroyed the Clinton email archive after — not before — Congress had issued a subpoena for it. If Combetta had immunity, why couldn't he talk to Congress? The question is particularly important since the FBI summary report on the Clinton affair says Combetta not only changed his story between interviews but refused to answer a few questions for the investigating agents, too.

"Congress should know the nature and scope of all immunity agreements reached between the Department of Justice and witnesses in this investigation," Gowdy said in a statement. "While there are media reports the person accused of actually destroying potential federal records while both a preservation request and a subpoena were in place was granted immunity, the DOJ has not confirmed this. Congress — and by extension the people we represent — are entitled to the full investigative file save the classified information. This will enable Congress and the public to know what kind of immunity was granted, for what potential criminal acts, and whether the individual granted immunity has an ongoing obligation to cooperate with government entities investigating the matters surrounding the extremely careless handling of classified information. That is what oversight is: reviewing the decisions made by other branches of government."

So what can Chaffetz, and Gowdy, and the House of Representatives as a whole, do now? Chaffetz was clearly most irritated at Pagliano, who wouldn't even come to the hearing, suggesting the committee will consider the "full range of options" in dealing with him. Presumably that meant possible contempt of Congress charges against Pagliano.

Perhaps Combetta and Thornton might face the same. But such moves, if they ever occur, will take a while. And what happens if the House finds someone in contempt? The matter is turned over to the Justice Department to pursue.

That would be the same Justice Department that never told Congress it had made an immunity deal with Combetta in the first place — and won't tell lawmakers now, either. It would be the same Justice Department that on Monday told lawmakers they could file a Freedom of Information Act request, just like anyone else, if they wanted to see more of the Clinton investigation documents. And it would be the same Justice Department that gave unusually wide latitude to the Clinton defense, allowing a material witness in the case (Cheryl Mills) to also function as a Clinton lawyer, and then rushed to announce the end of the Clinton investigation a short time after Clinton's single interview with the FBI.

And now key people in the Clinton email matter are, as Chaffetz said, thumbing their noses at Congress. Whatever lawmakers ultimately decide to do, they'll likely have to do it on their own.