Police stopped a 24-year-old woman pushing a swing that held the body of her dead, 3-year-old son in a Maryland park on Friday morning.
The mother was hospitalized for a medical evaluation. There was no sign of trauma to the child's body, according to The Washington Post.
The Charles County Sheriff's Department got a call before 7 a.m. from a resident who said the mother was in Wills Memorial Park, in La Plata, for "an unusually long period of time," TV station WJLA reported. La Plata is about 30 miles south of Washington.
Officers instantly saw that the child was dead, The Associated Press reported, and took his body to a medical examiner for an autopsy.
The boy's eyes were shut and there were signs of rigor mortis, Charles County Sheriff's Office spokeswoman Diane Richardson told HuffPost.
The mother was possibly in the park the day before and perhaps was there overnight, police said.
"It didn't appear that she was fully aware of what was going on, " Richardson said. "It's just a very sad situation."
It's unclear where the mother made her home, but the boy's grandmother "lives nearby," Richardson said.
This article has been updated to include comments from the Charles County Sheriff's Office spokeswoman.