A California woman who left her 1-year-old son in a hot car while she underwent a cosmetic procedure at a medical spa is now facing a murder charge.

Maya Hernandez, aged 20, attended a court session on Tuesday following her arrest earlier in the month related to the tragic passing of her son, Amillio Gutierrez. Initially charged with manslaughter and two counts of child cruelty, Judge Brian McNamara agreed to include a murder charge after considering the evidence presented by prosecutor Stephanie Taconi.

Local NBC affiliate WGET reported from the courtroom during the hearing, where witnesses and detectives who were present on June 29 testified. It was on that day Hernandez discovered her 1-year-old son Amillio unresponsive in the car.

According to WGET”s reporting on the hearing, detectives stated that surveillance video showed Hernandez arriving at the medical spa at 1:10 p.m. on June 29. She briefly left the car and returned to it, staying until 2:09 p.m., when she went back inside the medical spa. The next time she was seen returning to her car was 4:33 p.m., having left her 1- and 2-year-old children unattended for nearly 2 1/2 hours as the temperature rose to 101 degrees in the afternoon heat.

A nurse who treated Amillio when he was taken to the emergency room said that he had a temperature of 107.2 degrees. When he arrived, he was “pale with blue lips, feet and hands, unconscious and with no pulse.” Despite lifesaving measures, he was pronounced dead at 5:48 p.m.

A woman who was at the medical spa with a friend told the court that she had spoken to Hernandez in the waiting room. Hernandez mentioned that she had “two little babies,” but did not indicate that they were outside in the car. After Hernandez was finished with her procedure, she went outside and then came back in holding a child who appeared “limp” and “purple” and was making “gargling” sounds.

Someone else handed Hernandez’s 2-year-old to the woman, who said the older boy was hot to the touch and sweating. She brought the boy into the medical spa’s restroom to throw cold water on him and cool him down. A nurse who worked at the medical spa stated that the 2-year-old boy “looked like he was going to have a stroke.”

The same nurse stated that Hernandez “looked out of it, like she didn’t care what was going on.”

An autopsy conducted on Amillio revealed that his brain had begun to swell and other organs had started to fail by the time he died.

Prosecutors presented text messages that Hernandez exchanged with a staff member at the medical spa prior to her appointment. Hernandez specifically asked, “Thank you can I bring my kids by chance?” An employee of the medical spa responded, “Sure if you don’t mind them waiting in the waiting room hun.”

Several witnesses testified that there were other supervised children in the lobby, which was considered a safe place for them.

Detectives told the court that they staged a reenactment of the alleged crime scene on July 2 under nearly identical weather conditions and using Hernandez’s Toyota Corolla hybrid. They parked the car in the same spot and placed their body worn cameras inside the vehicle. Consistent with the known mechanism of the car that shut the vehicle’s engine off after one hour of running with no activity, the Corolla turned itself off at 3:09 p.m. on the day of the experiment.

The internal temperature of the car reached 116 degrees at 4:15 p.m. One of the body cameras shut itself off due to “critical internal temperature.”

Detective Kyle McNabb stated that when he interviewed Hernandez, she told him that she did consider the fact that the car could become too hot for her children to stay inside. She said she had left the air conditioner set at 60 degrees with the fan on a high setting. The car was left unlocked with the keys under the front seat.

He also stated that Hernandez acknowledged that her actions were irresponsible, and that she had heard radio ads warning of the dangers of leaving children in a hot car. McNabb stated that Hernandez told him, “It’s not like I left them in there for them to just f—ing die.”

Hernandez is now charged with first-degree murder, manslaughter, and two counts of child cruelty. She remains in custody on more than $1 million. Her arraignment is scheduled for July 24.