Law enforcement officials say an autopsy has been completed on a child who was found dead in a park swing as his mother pushed him, but the cause of death remains under investigation.

Charles County Sheriff's Office spokeswoman Diane Richardson said Monday that there were no findings on the cause or manner of death of the 3-year-old found Friday in La Plata, Maryland.

Richardson says further investigation and toxicology tests are needed. The 24-year-old mother was taken to a hospital Friday. Richardson said she was still hospitalized Monday. Officials haven't identified her. They've said she may have been at the park for hours before the boy was discovered.

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