Someone heard the children crying, but Hawkins said, "They'll cry themselves to sleep"
Credit: Facebook

A Texas mom admitted Monday to causing the deaths of her two toddlers in 2017 by leaving them in a hot car for at least 15 hours, PEOPLE confirms.

Amanda Hawkins pleaded guilty to two felony counts of abandoning or endangering a child causing imminent danger of death, bodily injury or physical or mental impairment and two counts of injury to a child. She faces between two and 20 years in prison when she’s sentenced on Dec. 12.

On the evening of June 6, 2017, Hawkins, then 19, drove her children — Brynn Hawkins, 1, and Addyson Overgard-Eddy, 2 — to a friend’s house in Kerrville, Texas, and left them in her vehicle overnight, where they endured the heat of the hot car while she was inside a nearby home with friends, according to law enforcement.

Authorities said the outside temperatures rose to the high 80s and that at some point in the evening, someone heard the girls crying and asked if they wanted to come in.

“She [Hawkins] said, ‘No, it’s fine. They’ll cry themselves to sleep,’ ” Kerr County Sheriff W.R. “Rusty” Hierholzer said in an interview with the Washington Post.

At about noon the next day, Hawkins got the girls from the vehicle and bathed them before taking them to the hospital, authorities said. Authorities said she feared the consequences of seeking medical help.

According to authorities, Hawkins took her daughters to a medical center in “grave condition,” claiming the girls had collapsed after smelling flowers during an outing in a local park.

Sheriff Hierholzer said authorities believe Hawkins had left her children alone in a vehicle previously but said the sheriff’s office had “no history” with her, local TV station KABB previously reported.

“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 after Hawkins’ arrest.

Amanda Hawkins
| Credit: Kerr County Sheriff's Office
Kevin Franke
| Credit: Kerr County Police Dept.

A second person, Kevin Franke, was also charged in the girls’ deaths. Franke was originally charged with manslaughter and abandonment, but those counts were replaced with two counts of first-degree murder, according to court records obtained by PEOPLE.

Franke allegedly told police he could not find a place inside Hawkins’ home to sleep, so decided to doze in the SUV, his indictment alleges.

• 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.

Franke claimed he did not know the children were in the car and did not hear them make any sounds.

The indictment alleges Franke rolled up the SUV’s windows and shut the engine off when he exited the vehicle at 8 a.m. on June 7.

He has pleaded not guilty to the charges and his trial is scheduled for Jan. 22.