Father Tells of Murder Suspect’s Unhappy Childhood : Trial: A jury is told that depression, anger and neglect dominated the young life of a baby-sitter charged with suffocating his crying, 15-month-old nephew.

The father of a Fountain Valley man charged with murdering his 15-month-old nephew testified Tuesday that his son has a history of depression and was neglected as a child.

As the defense presented its case in the trial of Sherman Robert Corwin Jr., his father also testified that his son was a perfectionist as a child and became visibly upset when he did not succeed.

“He’d take his fists and hit himself on the head,” Sherman Robert Corwin Sr. said, waving his own clenched fists toward his head. “The littlest thing would fire him up.”

Corwin Jr., 21, is charged with first-degree murder in the Oct. 14, 1989, death of Thomas Negri, his nephew. Corwin had been baby-sitting the child.

The father’s testimony came as the defense laid out its case that Corwin’s lack of adult guidance, coupled with a mental illness, contributed to his frame of mind the night he allegedly choked and suffocated his nephew to stop him from crying.

Greg and Cheryl Negri of Fountain Valley, the infant’s parents, have testified that they came home from dinner that night to find their son’s lifeless body in his crib and Cheryl Negri’s brother, Corwin, gone.

After his arrest, Corwin told police in a taped confession that he “lost control” when his nephew started crying in the night.

According to the tape played in court Monday, Corwin first put a plastic bag over the child’s head, then gagged him with a sock. When the child stopped breathing, Corwin said he panicked and placed the child’s body in a trash bag and knotted it.

Corwin’s attorney, public defender Marri Derby, told the jury that Corwin is mentally unstable because of a mental illness he inherited from his mother, who committed suicide when he was 7.

Also, he grew up neglected and unsupervised by his father, she added.

Several of Corwin’s friends and co-workers also testified Tuesday that they had often witnessed his unexplained periods of depression.

Corwin’s moodiness was more noticeable three weeks before the killing, they said.

Before presenting her defense, Derby asked Superior Court Judge Ragnar R. Engebretsen to have Corwin’s first-degree murder charge reduced to second-degree murder.

She called the prosecution’s claim that Corwin planned his nephew’s death “baloney.” Engebretsen denied Derby’s motion.