A Mississippi police officer has been suspended from duty following the death of her three-year-old daughter who died after allegedly being left unattended in a patrol car for up to four hours.

Local media reported that Cassie Barker, who works for Hancock County Police Department, was visiting the home of fellow officer Clark Ladner and left her daughter in the patrol car on a hot day. When discovered in the car, Cheyenne Hyer was "unresponsive".

Hancock County Chief Deputy Don Bass said the air conditioning was on when the girl was found, though it was unclear if it had been on all the time. Barker is reportedly on paid leave following her daughter's death.

"There's no logical reason to do that," Chief Deputy Bass told the Clarion-Ledger. "It's not an accident. She left the child in the car." Bass said if charges are filed, they would probably include negligent homicide.

However the same newspaper reports that the policewoman has been hospitalised and unable to sign papers releasing her daughter's body to a funeral directors. She is also said to be unable to speak to authorities about what happened.

Both officers are said to have been off duty when the incident occurred.

Officer Ladner is on paid leave while the investigation takes place though it is unclear if he knew Cheyenne was in the vehicle. The results of a postmortem are expected this week (October 2016).

According to Journal News, Barker had previously been involved in an incident which led the local Department of Human Services to become involved, and had to work with the agency to get her daughter back. Details of the incident have not been published.

Barker was also suspended for one week without pay in May 2015, according to minutes of a Board of Alderman meeting unearthed by the Clarion-Ledger, though again the reasons have not been published.