Dad convicted of "child abuse" in death of 4-month-old daughter; had blamed 2-year-old daughter for baby's fatal head injuries (Gresham, Nebraska)

Why is it when a father kills the baby, it's called "child abuse" and not "murder"? If this guy had been out on the street and had bashed in some other adult male's head, it would be murder, right? But it's not as bad as when it's just a 4-month-old baby? That's repulsive thinking in my book. 

Also, was there a mother in this home? Sure doesn't sound like it. Was this guy the "primary caretaker"? What? 

Dad is identified as RYAN KOZISEK.

http://www.wowt.com/news/headlines/Father-Who-Blamed-Toddlers-Injuries-On-2-Year-Old-188502951.html?ref=951

Posted: Sat 5:17 PM, Jan 26, 2013

Reporter: The Associated Press

Dad Who Blamed 2-Year-Old For Baby's Injuries Convicted Of Abuse

A Gresham, Nebraska man was found guilty Friday of child abuse resulting in the death of his infant daughter.

Attorney General Jon Bruning says 31-year-old Ryan Kozisek was convicted by a York County jury for the death of his 4-month-old daughter Kayley, who died at an Omaha hospital on January 25, 2011, a day after Kozisek called 911 and said she wasn't breathing. 

Kozisek told emergency crews that his 2-year-old daughter accidentally fell off a stepping stool and onto the baby. A doctor told investigators the baby's multiple injuries, including severe hemorrhaging and brain trauma, could not have been caused by a 2-year-old.