Democratic and Republican lawmakers are joining forces to demand the creation of an independent blue-ribbon commission to investigate the Jan. 6 storming of the U.S. Capitol.

Lawmakers say a commission similar to the one that probed circumstances surrounding the Sept. 11 terror attacks should be created to investigate all aspects of the deadly insurrection, including the role of former President Donald Trump, who was impeached for inciting insurrection but was acquitted Saturday in the Senate.

“There should be a complete investigation about what happened,” said Sen. Bill Cassidy, R-La., one of seven GOP senators who voted to convict Trump. “What was known, who knew it and when they knew, all that, because that builds the basis so this never happens again.”

Sen. Chris Coons, a Delaware Democrat and close ally of President Joe Biden, agreed that Americans still don’t know the whole truth about what happened, who is responsible and how it could have been prevented. “There’s still more evidence that the American people need and deserve to hear,” Coons said. “And that we lay bare the record of just how responsible and how abjectly violating of his constitutional oath President Trump really was.”

Investigations into the riot were already planned, with Senate hearings scheduled later this month in the Senate Rules Committee. Retired Army Lt. Gen. Russel Honoré is to lead an immediate review of the Capitol’s security process since Trump supporters easily overwhelmed outnumbered Capitol Police.

A 9/11-style commission would probably require legislation from Congress to create. That would elevate the investigation a step higher, offering a definitive government-backed accounting of events.