CHATTANOOGA, Tenn. (AP) — A judge is expected to decide whether to allow certain witness testimony at the trial of a Tennessee school bus driver charged in a fatal crash.

The Chattanooga Times Free Press reports that three people testified Monday that Johnthony Walker cursed out students and sped off in front of school administrators. Jasmine Mateen, the mother of one of the six Woodmore Elementary School children killed in the crash, said she often noticed Walker speeding or making sudden stops.

Authorities say Walker was speeding in November 2016 when he wrecked the bus in Chattanooga with 37 children on board. He faces 34 charges, including vehicular homicide.

Walker’s trial is set for Feb. 27. His lawyer said the emotional testimony distracts from issue of whether he operated the bus dangerously.