A former police officer has been jailed for 20 years over the death of her three-year-old daughter whom she left in her hot patrol car for four hours while she had sex with her supervisor.

Cassie Barker left Cheyenne Hyer in the back of the car while she went into her then-supervisor's home on 30 September 2016, The Sun Herald of Biloxi reported.

The 29-year-old ex-Long Beach police officer pleaded guilty to a lesser charge of manslaughter last month in a plea bargain after she was initially accused of committing second-degree murder.

Harrison County Circuit Court in Gulfport, Mississippi, heard that after the pair had sex, Barker fell asleep.

Cheyenne was strapped in her patrol car with the air conditioning on, but it was not blowing cold air.


When Barker eventually emerged from the house she found her girl unresponsive and attempted to give her CPR, but when paramedics arrived at the scene they found no pulse.

Image: Former Long Beach police officer Cassie Barker. Pic: Sun Herald

The toddler had a temperature of 42C (107F) when she was pronounced dead.

Barker and her supervisor, who at the time claimed he did not know Cheyenne was in the car, were fired over the incident.

"I can appreciate you loved the child, but you left the child - your own flesh and blood - in a car while you went into the air-conditioned house while you had sexual relations," Judge Larry Bourgeois told a pregnant Barker as he sentenced her on Monday.

"When you have a child and you bring this child into the world, it also brings responsibility.

"I don't know how to put it other than you have failed in the responsibility of this child."

The girl's father, Ryan Hyer, told the judge: "Every time I see a patrol car, I see Cheyenne gasping for air."