At first, officials said, a 19-year-old Texas mother claimed her two young daughters were ill because they probably ingested some wild flowers — but another story quickly began to emerge.
On the evening of June 6, Amanda Hawkins allegedly drove her children to a friend’s house and left them in her vehicle overnight, where they endured the Texas heat for at least 15 hours while she was inside a nearby home with friends, according to law enforcement.
Authorities said that at some point in the evening, someone heard the girls — who were 1 and 2 years old — crying outside and asked if they wanted to come in.
Hierholzer, who did not return PEOPLE’s calls for comment, also said that a 16-year-old friend with Hawkins went outside to her car at some point and slept for a period of time but returned to the home, local TV station KABB reports.
The girls did not have food or water while in the vehicle, Hierholzer told the station.
• Want to keep up with the latest crime coverage? Click here to get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter
Around noon the next day, Hawkins got the girls from the vehicle and bathed them before taking them to the hospital, authorities have said. She allegedly feared the consequences of seeking medical help.
“Best we can tell, they [the children] were probably unresponsive,” Hierholzer told the Post.
According to one local weather report, temperatures in the area dipped to 65 degrees overnight Tuesday before climbing to 92 degrees on Wednesday.
Brynn Hawkins, 2, and Addyson Overgard-Eddy, 1, later died at University Hospital in nearby San Antonio, Texas. Full autopsies are being conducted, which include toxicology reports.
A final determination of the girls’ cause and manner of death won’t be available for up to 12 weeks, officials from the Bexar County, Texas, Medical Examiner’s office told PEOPLE.
Meanwhile, a warrant was issued for Hawkins’ arrest but she has not been indicted, a county official told PEOPLE. A grand jury is expected to meet on Monday.
Hawkins, from Kerrville, Texas, was charged with two counts of child endangerment and her bond has been set for $70,000, according to court records. She remains in custody and has not entered a plea, and it is unclear if she has retained an attorney.
Sheriff Hierholzer said that investigators believe Hawkins has left her children alone in a vehicle before but that the sheriff’s office had “no history” with her, according to their records, KABB reports.
“This is by far the most horrific case of child endangerment that I have seen in the 37 years that I have been in law enforcement,” Hierholzer said in a statement on Friday, adding that the charges against Hawkins could be upgraded after the case is presented to a grand jury.