Washington -- Democratic Rep. Adam Schiff, California, is a member the House select committee that investigated the Jan. 6 attack on the U.S. Capitol. He harshly criticised a Justice Department decision not to prosecute two top Trump aides for defying congressional subpoenas.

In an interview on Sunday with Face the Nation, Schiff stated that it was "puzzling” that the Justice Department refused to indict Mark Meadows, former chief of staff to the White House, and Dan Scavino, former deputy chief, for refusing cooperation with House investigators. But, they did indict Peter Navarro, former White House adviser, and Trump ally Steve Bannon.

"There is no absolute immunity. Schiff stated that these witnesses have very pertinent testimony to offer regarding the events surrounding Jan. 6 violence, the propagation and continuation of the big lie." "The notion that witnesses might simply not show up is deeply troubling. The statute requires the Justice Department present the cases to the grand jury.

Schiff stated that the select committee would like to hear more from the Justice Department about Meadows and Scavino but added that it was a "grave surprise" and could hinder our work if other witnesses feel they can, likewise refuse to appear with impunity.

Meadows, Scavino and Navarro were summoned to testify before House investigators in the course of their investigation into the Jan. 6 attacks. However, all four refused subpoenas. The full House voted to indict all four of them for criminal contempt of Congress.

Although Navarro, Bannon and Meadows refused to cooperate with the select committee's work, Scavino and Meadows engaged in negotiations with lawyers from the committee. Meadows provided 9,000 pages worth of emails and texts to the panel before he decided to stop cooperating.

Schiff stated that Trump's two closest aides could testify before the committee without any "plausible claim of executive privilege" as they were both involved in campaign issues and had records they could give to investigators.

He warned that "none of these is protected by privilege" and that a person can refuse to appear and instead say, "As to the question, I'm going o exert a privilege," that invites others to be contemptuous of Congress or to be contemptuous of judges across the country and it's a dangerous precedent to set."

Nearly one year after its investigation into Jan. 6 events and Trump's attempts to block the presidential transfer, the select committee is ready to present its findings before the American people. The first hearing will be held in primetime on Thursday.

The panel stated that they would present previously unseen material on January 6, hear witness testimony, view additional hearings and give the American people a summary about its findings regarding the coordinated multi-step effort to reverse the 2020 presidential election results and prevent the transfer or power.

Schiff stated that this week's hearing is the first of nine. He said that the committee members are expected to present the "narrative of what happened in the country, how close were we to losing democracy, and what led to the violent attack on the 6th."

"I think the American people know a lot already. They have seen many bombshells. He said that there is a lot more they haven’t seen. The most important thing is that the public has not seen how it all came together. They haven't seen how one thing led into another. It hasn’t seen how one line of efforts to overturn the election led another. This ultimately led to terrible violence and the first non-peaceful transfer in human history.

Although Schiff would not comment on the testimony of Marc Short, the former chief of staff of Vice President Mike Pence's, Schiff stated that one of the "themes," which the panel will be examining, is the fact that there was an understanding about the propensity to violence on Jan. 6. This was due to the participation by far-right extremist organizations and the continual spreading of the so called "big lie" -- namely, that Trump stole the 2020 election -- to anger Trump's supporters.

The New York Times reported the first time, and CBS News confirmed that Short had warned the Secret Service the day prior to the attack on Jan. 6.