SIOUX FALLS, S.D. (KELO) — Not guilty – that’s the plea for a Sioux Falls man accused of killing his infant son. Dylan Castimore returned to court Monday morning.

He looked down as the judge read through his new charges, which include first degree murder and aggravated battery of an infant. The judge explained that if he’s found guilty of first degree murder, he will either face a mandatory life sentence or the death penalty.

When asked if he understood the charges, Castimore said, “Yes, your honor,” and the judge entered a not guilty plea on his behalf.

Castimore’s son – eight-week-old Daxton – died at Avera McKennan Hospital on November 27. According to an autopsy, the infant died of a skull fracture. Court documents say Daxton also had a lacerated liver, bruising and broken ribs.

Days earlier, Castimore brought the baby to an emergency room with scratches and a black eye.