The first-degree homicide trial of a Butler County man accused of killing the 14-month-old son of his girlfriend is set to open today.

The jury of 12 with four alternates has been individually questioned and "death-penalty qualified" because District Attorney Richard Goldinger has indicated he will argue that Jarred Burton Knight, 24, should be executed if he is convicted.

Tyler Davis died June 24, 2007, of blunt force trauma to the head. The doctor who conducted the autopsy on the toddler likened the injury to a fall from a 20- to 30-story building.

The child lived outside Harrisville with his mother, Jessica Davis, and Mr. Knight. He was being baby-sat by Mr. Knight when he was injured on June 23.

The defendant told police the boy began throwing a tantrum as he readied him for a bath and that the child banged his head on the side of the ceramic tub and on the floor. Mr. Knight later told police he tripped over the family dog while running with the child after the initial incident and that he fell on the child, who may have hit the floor.

Prosecutors contend Mr. Knight had learned about a month before Tyler's death that he was not Tyler's biological father.

Mr. Knight is being represented by attorney Mike DeRiso of Pittsburgh and Butler County Public Defender Kevin Flaherty. In addition to homicide, he is charged with child endangerment and reckless endangerment.

He will be tried before Judge Tim McCune.

The jurors will be allowed to return home at the end of each trial day. Deputy Court Administrator Tom Holman said the courtroom schedule has been cleared for two weeks.