Four police officers offered harrowing testimony of their experiences protecting the U.S. Capitol on January 6th during the first hearing for a new Democrat-led House Select Committee investigating the attacks.

The committee was proposed as a bi-partisan effort by House Speaker Nancy Pelosi but after she rejected two nominees from Minority Leader Kevin McCarthy, the hearings have begun without support from Republican leaders.

Since January 6th the Justice Department has arrested hundreds of people who were at the Capitol. NPR Investigations Correspondent Dina Temple-Raston reports that while those cases initially seemed like they’d be a slam dunk, the process of bringing them to trial has proved more difficult than anyone could have imagined.