"Primary caretaker" dad who killed 9-week-old son dies in prison (Canon City, Colorado)

So basically this "primary caretaker" daddy tortured this baby from birth to the time his life was mercifully cut short at just 9 weeks. Like so many male "caretakers," Dad just couldn't tolerate a crying baby. So instead of comforting the baby, he'd just bash him.

Dad is identified as JOSEPH DOWLER.

Why was this not considered 1st-degree murder?

http://www.thedenverchannel.com/news/local-news/joseph-dowler-sentenced-to-60-years-in-babys-death-dies-in-prison

Joseph Dowler, sentenced to 60 years in baby's death, dies in prison
Posted: 11/19/2013
Last Updated: 1 day ago

Deb Stanley TheDenverChannel.com Team

CANON CITY, Colo. - A father convicted of child abuse resulting in the death of his 9-week-old son has died in prison.

Joseph Dowler was sentenced in 2003 to 60 years in prison. He died November 6 at the Colorado Territorial Correctional Facility in Canon City, according to a news tip sent to 7NEWS and confirmed by the Boulder Daily Camera. Dowler was 45.

In October 2002, Dowler's son Tanner was brought to Community Medical Center in Lafayette barely breathing and ''gravely ill,'' a doctor testified at Joseph Dowler's trial.

Tanner died after being taken off life-support equipment.

Doctors said Tanner had signs he had been severely beaten or shaken on more than one occasion. He died of brain injuries, but doctors said the baby had 11 broken ribs and second- and third-degree burns on both feet when he was taken to the hospital. He had been shaken so hard that parts of his eyeballs had separated.

At trial, a detective told the jury that Joseph Dowler confessed to twisting his son's arms until they popped and to lifting him by his jaw to get his attention.

Dowler's defense team tried to shift some of the blame on the mother -- Audra Dowler. Dowler, 19, was sentenced to 10 years in prison for negligence in connection with Tanner's death. She was released after serving about three years, the Camera reported.

Audra Dowler testified that Joseph was the primary person who took care of the baby and he was often frustrated by the boy's crying. She said her husband balked at getting their son medical attention because he was concerned he would be accused of child abuse.

Joseph Dowler was convicted on seven counts of child abuse resulting in serious bodily injury, but was found not guilty of first-degree murder.

Read the Colorado Department of Human Services report on Tanner Dowler: http://www.thedenverchannel.com/news/full-report-on-tanner-dowler-s-death-by-department-of-human-services