SANTA ANA (CBSLA.com) — A La Habra woman pleaded not guilty Wednesday to charges of throwing her 7-month-old son off of a hospital parking garage.

KNX 1070′s Ron Kilgore reports Sonia Hermosillo has been in custody since August of 2011 on murder and child abuse charges.

Hermosillo, 32, pleaded not guilty by reason of insanity in the death of her son, Noe Medina, Jr., who was killed after a fall from the fourth level of a parking structure at Children’s Hospital of Orange County.

Hermosillo’s husband, Noe Medina, told reporters his wife suffered from postpartum depression and was distraught that their son had a medical condition that required him to wear a helmet.

Prosecutors say Hermosillo removed the helmet before tossing the baby off the parking structure and dropping him to the pavement some 40 feet below. The baby was taken off life support two days later.

Attorney Jacqueline Goodman said doctors have been appointed for the trial in the event that an evaluation is needed.

“That question is one of what was her mental state at the time of the accident, and if she’s found guilty – we hope she isn’t – then there comes a phase of the trial to determine whether mental illness is what caused the accident,” said Goodman.

Deputy District Attorney Scott Simmons has previously stated that Hermosillo’s decision to remove the boy’s helmet indicated forethought.

Bail was set at $1 million for Hermosillo, who is believed to be an undocumented immigrant and is also subject to an immigration hold.