The trial of a Texas police officer charged over his response during the 2022 attack at Robb Elementary entered a second week Monday, as prosecutors continued pressing their case that Adrian Gonzales did nothing in the early moments to stop the gunman.

Gonzales, 52, a former Uvalde schools police officer, has pleaded not guilty to 29 counts of child abandonment or endangerment. The May 24, 2022, shooting is among the worst school shootings in U.S. history, killing 19 students and two teachers.

Prosecutors said the case focuses on one officer rather than the larger, broader response from law enforcement that day. Gonzales was among the first officers to arrive as the gunman approached the school, and the AP report said it would take more than an hour for a tactical team to go into a classroom and kill 18-year-old shooter Salvador Ramos.

In the trial’s framing, prosecutors allege Gonzales abandoned his active shooter training and did not try to engage or distract the gunman outside the school. They also allege a second failure minutes later, when a group of officers went inside the school only to retreat when they came under heavy gunfire.

Prosecutors emphasized 911 calls made by students from inside the classroom with the gunman, and special prosecutor Bill Turner told jurors, “When a child calls 911, we have a right to expect a response.”

Gonzales’ attorneys, by contrast, have said he never saw the gunman outside the school. They also said Gonzales helped students evacuate from other classrooms, and they pointed to how the gunman was able to quickly get inside through an unlocked door.

Testimony in the first days included family accounts and descriptions from teachers about following active-shooter training during the attack. Jennifer Garcia told jurors that her 9-year-old daughter, Eliahna Garcia, asked to leave school early after an awards program, and she said she told her, “No … stay at school.” Garcia also told jurors that the family was among the last to learn that night that their daughter had died.

Teachers described the terror of seeing the gunman approach and hearing gunfire, including Lynn Deming, who was wounded by shrapnel when a classroom window was shot out. Deming said, “I told them I loved them,” and added: “I wanted to tell them it would be OK, but I wasn’t sure,” and “I wanted to make sure the last thing they heard was that somebody loved them.”

Jurors also saw photos from the classrooms, including images showing large amounts of blood and the dead gunman. A medical examiner described wounds to children, noting several were shot at least a dozen times.

Prosecutors also focused on evidence described as a trail of bullets and shell casings left as the gunman fired outside the school. They hope to show the jury that Gonzales should have been close enough to see the gunman shooting and confront him in the early moments.

The AP report said prosecutors ran into a setback when the testimony of the first teacher to testify was dismissed by the judge. The defense had complained that the teacher’s detailed description of the gunman was new evidence that was not disclosed before trial; the judge denied the defense request for a mistrial but instructed the jury to disregard the testimony.

The trial is described as rare because it is a case in which a police officer could be convicted of allegedly failing to act to stop a crime and protect lives. Gonzales and former Uvalde schools Police Chief Pete Arredondo are the only two responding officers that day facing charges, and Arredondo’s trial has not yet been set.

Prosecutors may face a high bar, the AP report noted, pointing to an acquittal in the Parkland, Florida, school massacre in 2018, when a Florida sheriff’s deputy was acquitted after being charged with failing to confront the shooter. The report said that Parkland case was the first such prosecution in the U.S. for an on-campus shooting.