LINCOLN, Neb. (AP) — A Lancaster County judge has declared a mistrial in the assault case of an inmate accused of punching a prison guard in the face.

40-year-old Timothy Schrader does not deny punching the guard, but has maintained that he did so to protect himself after he learned of a plan by other inmates to stab him.

Schrader’s attorney says Schrader knew if he hit a guard, he would be put in segregation away from other inmates.

But prosecutors argued that his choice to punch a guard — even to ensure his own safety — was still a crime.

Jurors began deliberating the case Friday morning, and by late afternoon came back deadlocked. The judge then declared a mistrial.