WASHINGTON — Many questions remain unanswered about the failure to prevent the Jan. 6 insurrection at the U.S. Capitol. But after six congressional hearings, it’s clear that the Capitol Police were unprepared and overwhelmed as hundreds of Donald Trump’s supporters laid siege to the building. It’s also clear that no one wants to take responsibility for it. Officials who were in charge of protecting the Capitol, and the people inside it, have pointed fingers at each other in testimony to the House and Senate.