The decision by Mississippi police officer Cassie Barker to leave her 3-year-old daughter outside in her patrol car on a 100-degree day while she had sex with her supervisor had fatal consequences for the child.

Fours hours after exiting the car with the air conditioner blowing, Barker returned to find her daughter, Cheyenne Hyer, unresponsive. The child was rushed to a hospital; officials said her body temperature topped 107 degrees. She died from heatstroke.

On Monday, Barker was sentenced to 20 years after pleading guilty to manslaughter in the 2016 incident, leading the 3-year-old’s father, Ryan Hyer, who was separated from Barker, to mourn the loss of the girl as his “innocent angel.”

Pregnant now by another man, the 29-year-old Barker will begin serving her sentence as an expectant mother — but the new child is not the former supervisor’s, Barker’s attorney tells PEOPLE.

“The father is not the same officer who was her former supervisor that was present with her at the time of the incident,” says the attorney, Damien Holcomb. “She did tell me it wasn’t him. I’m not sure who the actual dad is. … She just hasn’t released that to me, and I haven’t asked.”