Ten people were killed in March 2021 at a King Soopers supermarket in Boulder, Colo. The gunman has pleaded not guilty by reason of insanity.

The fate of a gunman now rests in the hands of a 12-person jury, who are tasked with determining not if he committed the heinous act, but whether he was legally insane when he drove to a Boulder, Colorado grocery store and opened fire, killing 10 people on March 22, 2021.

Prosecutor Ken Kupfner loaded dummy bullets into a 30-round magazine in a hushed courtroom Friday morning. He slowly pushed each bullet into the magazine — the same type of magazine used by the man who carried out a mass shooting at a Boulder King Soopers grocery store in 2021,