SANTA ANA – A 36-year-old La Habra mother accused of pushing her infant son off a parking structure to his death in 2011 has been found mentally fit to stand trial.

Sonia Hermosillo has been in custody for more than five years as attorneys argued over her mental state. A judge previously found her to be mentally competent, but another evaluation determined her to be mentally unfit and she was committed last year to Patton State Hospital in San Bernardino.

In a final evaluation, an Orange County Superior Court judge on Monday determined that Sonia Hermosillo is now mentally fit to assist in her defense after a report from the hospital medical director said she has been under treatment and is capable of understanding the criminal proceedings.

She has been transferred to the Orange County Jail and is due back in court on Nov. 16 for a pre-trial hearing.

Hermosillo has pleaded not guilty by reason of insanity to charges of murder and assault on a child causing death. If convicted, she faces 25 years to life in prison.

In a case that made national headlines, Hermosillo drove to the parking structure at Children’s Hospital of Orange County, where her 7-month-old son, Noe Hermosillo Jr., was receiving treatment for a congenital problem because his neck twisted to one side.

Authorities said Hermosillo removed her son’s helmet, which he wore for another condition known as flat-head syndrome, then pushed him from the fourth floor of the parking structure. She then validated her parking permit before driving off but later returned and was arrested.

The boy died two days later.

Senior Deputy District Attorney Scott Simmons said there is evidence that Hermosillo was aware of what she was doing and deliberated before pushing the baby over the edge.

Her defense attorney, Jacqueline Goodman, maintains that Hermosillo, who has two older daughters, was mentally ill and suffered from post-partum psychosis after the birth of her third child.

Goodman said Hermosillo developed her illness during the pregnancy and suffered a psychotic break as her husband desperately tried to get her help.

Goodman said Hermosillo received inadequate mental-health care in the months prior to the incident.

“This case should serve as the tragic example of the real-life consequences of blame, shame and misunderstanding of mental illness, in general, and postpartum, in particular,” she said.

Contact the writer: kpuente@ocregister.com