A former Mississippi police officer is facing two decades behind bars after she admitted to having sex with her supervisor while her child was dying in an overheated patrol car.

The defendant, 29-year-old Cassie Barker, pleaded guilty to culpable negligence manslaughter in the death of her 3-year-old daughter Cheyenne Hyer. Barker was originally indicted on second-degree murder charges, but received a reduced charge as part of a plea agreement, according to the Sun Herald.

Prosecutors have recommended a 20-year sentence for the ex-cop, Circuit Judge Larry Bourgeois said he wanted more time to think about the sentencing.

"I don't know what I could ever do to you that could be worse than what you’ve already experienced," Bourgeois said in Harrison County Circuit Court on Monday. "You will forever be entombed in a prison of your own mind."

Cheyenne died Sept. 30, 2016, after her mother left her strapped into a car seat for four hours while temperatures surpassed over 100 degrees. The Sun Herald reports Barker left the air conditioner on for the child, but it was not blowing cold air. When the mother returned to the vehicle, she found Cheyenne unresponsive.

Barker was fired from the Long Beach Police Department, along with her supervisor Clark Ladner. The mother said she had gone to Ladner's house after they both got off work on a hot morning. Barker told the judge she and Ladner fell asleep after having sex. Ladner has not been charged with any crime, and reportedly told officials he was unaware the child was in the car.

This wasn't the first time Barker left her daughter unattended inside a vehicle. In April 2015, child welfare services took temporary custody of Cheyenne after she was spotted inside a car parked in front of a store. Barker received a one-week suspension from the police department due to the incident.

Cheyenne's father, Ryan Hyer, is reportedly suing the Long Beach Police Department and Mississippi Child Protection Services for the death of his child. He claims he was never notified about the April 2015 incident and that Mississippi officials did not take enough action against Cheyenne's mother.

"Every time I close my eyes, I picture her suffering and then I picture her laying in this coffin," Hyer said. "I still see her smiling and laughing in my head and I would assume that smile and laughter turned to pain and suffering in that instance. It’s an image I don’t want to have, but it’s one I can’t get rid of."

Barker's sentencing will take place April 1.