Autopsies released by Arizona authorities have confirmed that the baby and toddler found dead while strapped in their car seats in a vehicle in March perished from exposure, multiple outlets report.
According to the autopsy, which was released by the Tuesday by the Pinal County Medical Examiner’s Office and obtained by multiple outlets, there was no evidence of trauma and no drugs in the systems of 2-year-old Lorenzo Velasquez and 9-month-old Brooklyn Velazquez, according to the Associated Press.
Brittany Velasquez, 21, the mother of the children, has been charged with second-degree murder and two counts of child abuse, and has pleaded not guilty, the Arizona Republic reports.
On March 26, authorities responded to a call at about 11:15 p.m. “after two children … were found deceased in a vehicle,” according to a statement from the Pinal County Sheriff’s Office obtained by PEOPLE, which added that “both children were found in the vehicle strapped in their car seats.”
The autopsies state that officials from the sheriff’s office alleged Velasquez had left the baby in the car at least twice in the past “for a prolonged period of time,” the AP reports.
The outlet also reports that the temperature the day they were found dead rose to 75 degrees, according to the National Weather Service.
Brooklyn and Christopher Velasquez
Two months before the kids died, Velasquez’s family told authorities the young mom was having difficulties taking care of them, PEOPLE learned in March.
Velasquez was investigated by the Arizona Department of Child Safety twice for alleged neglect, and local police visited the house multiple times over the last few years, sometimes after calls from a concerned relative, ACB15 reported in March.
Pinal County Sheriff’s Office
In a statement to PEOPLE in March, the DCS confirmed they received two reports of alleged neglect in the past but found no evidence of abuse.
Family members told local media Velasquez was mentally unstable.
In an interview with local station FOX10, Velasquez’s brother, Vincent, alleged his sister had been suffering from mental illness since she was young. Calling her “deranged,” Vincent told the station she allegedly refused to get help.
In its statement to PEOPLE, DCS said: “While there were concerns raised regarding Ms. Velasquez’s previous mental health, no evidence was presented by anyone that indicated mental health issues were impeding Ms. Velasquez’s ability to parent.”
In a jailhouse interview with FOX10 approximately two weeks after the deaths, Velasquez said she left her kids with a babysitter the day they died, and said she felt “betrayed” by the sitter.
But according to court documents obtained by the outlet, Velasquez never left her kids with a sitter. Velazquez had at one point also allegedly blamed the children’s grandparents, accoriding to the court documents.
PEOPLE was unable to reach an attorney for her. She is scheduled for an Aug. 10 pretrial conference, according to online jail records.