Sheriff's deputies responded Kaiser Permanente Medical Center in Santa Clara on Thursday on reports of a 4-month-old girl who had been transferred from the Kaiser facility in Hayward in critical condition, Alameda Sheriff's Sgt. J.D. Nelson said.
Nelson said doctors had determined the girl had suffered injuries consistent with being shaken and that investigators then began interviewing the girl's family members.
Her father, Jose Arevalo, was arrested Thursday on suspicion of child abuse. However, the girl's condition worsened on Friday and she was pronounced brain dead on Saturday, prompting the sheriff's office to amend his charge to murder.
"It sounds like the baby had been crying and he basically just lost it," Nelson said.
He said multiple family members live at the unincorporated Hayward home and that there were no other signs of abuse, and that everyone seemed to be in good health.
District attorney's spokeswoman Teresa Drenick said Arevalo was arraigned in Alameda County Superior Court in Hayward this afternoon on murder.