MORENO VALLEY, Calif. -

Opening statements are scheduled today in the trial of a Moreno Valley man accused of fatally beating his 2-year-old son.

Alexandro Alfonso Baeza, 27, could face 25 years to life in prison if convicted of murder and assault on a child resulting in great bodily injury in the April 2010 death of Isaac Gallegos.

Baeza is being held in lieu of $1 million bail at the Robert Presley Detention Center in Riverside.

According to a trial brief filed by Deputy District Attorney Burke Strunsky, Isaac died from cerebral hemorrhaging caused by a blow to the head or violent shaking.

On the day he was injured, the toddler was with his father alone in the defendant's Moreno Valley home. According to Strunsky, Baeza had limited custody of his son, who spent the majority of the time with his mother, Andrea Gallegos.

The Fontana woman had documented previous injuries on Isaac that she believed were the result of beatings and told as much to a family court judge in San Bernardino, but she was accused of making up the allegations in order to gain exclusive custody rights, according to court papers.

On April 10, 2010, Baeza called 911 and reported his son was in respiratory distress. The boy was rushed to Riverside County Regional Medical Center in Moreno Valley, where doctors discovered he was bleeding cranially, to the point that his brain was ``actually pushing out from his skull,'' Strunsky wrote.

Surgeons determined there was nothing they could do, and Isaac died three days later.

Under questioning by sheriff's detectives, Baeza initially said Isaac had started breathing abnormally as he was changing the child's diapers on his bed, according to the trial brief.

When investigators challenged the story, Baeza ``admitted that while changing his son's diaper, he jerked the diaper up from under Isaac, causing him to fall and hit his head on the floor,'' Strunsky wrote. ``Defendant described the floor as `very hard,' (but) investigators noted that the floor in the bedroom was, in fact, carpeted and padded.''

The cause of death was determined to be blunt force trauma.

According to Strunsky, Baeza was allegedly under the influence of methamphetamine at the time of his arrest.