A mistrial was averted on the second day of the trial of Adrian Gonzales, a former Uvalde, Texas, school police officer accused of endangering dozens of students during a deadly mass shooting at Robb Elementary, despite Gonzales’ defense team contending that the prosecution withheld key testimony.

Judge Sid Harle denied the defense’s motion for a mistrial on Wednesday and said the prosecution had merely been “negligent” after one of its witnesses revealed new information on the stand that she’d not previously disclosed.

Prosecutors allege that Gonzales failed to follow his active shooter training during the 2022 mass shooting that killed 19 children and two teachers.

Stephanie Hale, a former third-grade teacher at Robb Elementary, testified on Tuesday that she was outside on the south side of the school during her students’ recess time on May 24, 2022, when she got word to get inside. As she was ushering her students into the school, she said, she saw the shooter walking toward a door. Hale said she ran into the school with her students and hid in a classroom with them.

During cross-examination, the defense questioned Hale about seeing the shooter on the south side of the school because, according to the defense team, Hale had not revealed this information in an interview with police four days after the shooting, nor in her grand jury testimony. The defense said Hale’s revelation matters because their argument during opening statements was that Gonzales was on the south side of the school and never saw the shooter.