The trial for former Uvalde schools police officer Adrian Gonzales began Tuesday, in which he is charged with child abandonment or endangerment in the 2022 shooting that killed 21 people.

Gonzales was one of the first officers to respond to the school shooting in Texas, but they waited more than an hour to confront the shooter, Salvador Ramos, who killed 19 students and two teachers at Robb Elementary School, NBC News reported.

The former police officer faces 29 counts of child abandonment or endangerment and has pleaded not guilty to the charges.

Prosecutor Bill Turner, in his opening statement on Tuesday, accused Gonzales of failing to distract, delay and impede the shooter while he waited for help to arrive.

Gonzales' attorney, Jason Goss, argued that his client did the best he could with the knowledge he had at the time, noting that the former officer was navigating an active shooter situation and attempting to assess who the gunman was and where the gunfire was coming from.

Judge Sid Harle, who is overseeing the trial, said that the proceedings are expected to last about two weeks. A panel of 12 jurors and four alternates was selected on Monday after about 100 people were dismissed from the jury pool for saying they had already formed opinions on the trial.

Roughly 400 officers from state and federal agencies responded to Robb Elementary on May 24, 2022, after receiving calls of an active shooter. About 77 minutes lapsed from the time they arrived until a tactical team entered the classroom and killed the shooter.

Gonzales and former Uvalde schools police chief Pete Arredondo were among the first to arrive on the scene of the shooting, and are the only two officers to face criminal charges over the response. Arredondo’s trial has yet to be scheduled.

If found guilty, Gonzales could face a maximum sentence of two years in prison.