FURTHER INVESTIGATION AND toxicology tests are needed in the case of a Maryland child who was found dead in a park swing as his mother pushed him.

An autopsy has been completed on the three-year-old boy found Friday in La Plata, Maryland, but the cause of death remains under investigation, Charles County Sheriff’s Office spokeswoman Diane Richardson said Monday.

The 24-year-old mother was taken to a hospital Friday. Richardson said the woman remained hospitalised yesterday. Officials haven’t identified her. They’ve said she may have been at the park for hours before the boy was discovered.

Detectives were working to establish a timeline of the days before his death, Richardson said. Previously, she said there were no obvious signs of foul play but that it hadn’t been ruled out.

Also Monday, a woman who identified herself as the child’s maternal grandmother, told a TV station her daughter had been diagnosed with a mental illness a few months ago and had been seeking help. She didn’t give specifics.

The woman, who identified herself as Vontasha Simms, also told WUSA-TV her daughter ordinarily “would never harm my grandson in any type of way.”

Police have not commented on details of the investigation or whether mental illness played a role.

Read: Woman found pushing her dead son on swings >