Donald Trump has escaped from his second impeachment, and some would say that, after four years of misrule, the nation has escaped from him.

That might sound like a good deal, but it’s not. Too many questions still linger about the failed insurrection of Jan. 6, and no one has been held accountable for a crime against democracy. Since the U.S. Senate hasn’t taken every possible step to prevent this from happening again, we will have to look elsewhere.

Some good news has emerged from the impeachment: A majority of Americans and a bipartisan majority of the Senate agreed that Trump had falsely convinced a large number of his supporters that he had been the true winner of the 2020 presidential election. He called them to Washington on the day the Electoral College votes were to be certified and personally sent them to the Capitol building to disrupt the process.

The ensuing riot killed five people, including a police officer, and put a violent mob in the middle of the peaceful transfer of power for the only time in our history.

Maine can be proud that both of our senators, Susan Collins and Angus King, voted to convict Trump and made strong statements justifying their votes.

Collins, one of only seven Republicans to cross the aisle and vote to convict, said Trump’s incitement started long before Jan. 6.

“President Trump had stoked discontent with a steady barrage of false claims that the election had been stolen from him,” she said on the Senate floor. “That set the stage for the storming of the Capitol for the first time in more than 200 years.”

King, an independent who caucuses with Democrats, said the ultimate question was whether any of the events of Jan. 6 would have happened “but for” the actions of the then-president. “The answer is clear: of course not. Donald Trump poured the gasoline, lit the match and directed the hostile crowd towards Capitol Hill – he bears ultimate responsibility.”

But 43 Republican senators decided that Trump should escape any consequences, denying the impeachment the two-thirds vote necessary for a conviction.

The verdict leaves us with some strange results. Donald Trump moves into his ex-presidency as the most formidable figure in Republican politics, while Collins is facing rebuke from the Maine Republican Party, whose members “strongly condemn” her vote, according to a letter from party leaders. Considering that Collins is the only Republican in Washington elected from a New England state, and she was just re-elected with 57,000 more votes in Maine than Trump got while losing the state, maybe party leaders should be asking her advice, not rebuking her.

A conviction in the Senate would have drawn a clear line on the limits of presidential power going forward. The acquittal does not say how far is too far, leaving mob violence as an option for future presidents.

This verdict makes an investigation by a bipartisan commission all the more important. We need a full accounting about what happened in the Capitol and, more importantly, why it happened.

We need to develop an understanding of the intelligence and security failures that left the U.S. Capitol Police outnumbered and unprepared for an assault that was organized in plain sight on social media. But the probe shouldn’t stop there.

Who are the extremist groups that engaged in the attack? How much do they cooperate with each other? What allies did they have inside the government who helped them get ready for the big event?

These are the kinds of questions that need to be asked, and like the 9/11 Commission, the investigators need subpoena power to compel testimony from unfriendly witnesses.

The verdict in Donald Trump’s second impeachment trial should be a disappointment for anyone who cares about democracy and the rule of law. But it should not be the last word.

If we want to make sure that it doesn’t happen again, we need to be clear about what happened and who was responsible.