The boy's mother has been identified by the Washington Post as 24-year-old Romechia Simms. Simms' family told the newspaper that she had suffered from bipolar disorder and depression, but would have never hurt her son.
The father of her son, James Lee, told the Washington Post he had recently fought for full custody of Ji'Aire in court.
He had cited Simms' history of instability, including an incident where she allegedly jumped from a moving cab and was hospitalized.
However, Simms had argued she had recovered since her hospitalization. Earlier this month, the former couple agreed to joint legal custody of the child.
The autopsy of a 3-year-old found dead as his mother pushed him on a swing did not reveal the cause of the boy's death, the Associated Press reported Monday.
The boy's 24-year-old mother, meanwhile, remained hospitalized as the investigation into how the child died continued, authorities told the AP.
A sheriff's deputy found the mother Friday at a Maryland park pushing her dead son on the swing, possibly for hours.
Authorities believe the toddler had been deceased for several hours when the deputy found her, and that the mother may have been pushing him on the swing at Wills Memorial Park in La Plata, Maryland, since the previous day.
"She was able to answer some questions for us," Diane Richardson, a spokeswoman for the Charles County Sheriff's Office, told BuzzFeed News Friday.
Deputies were called at 7 a.m. when a resident near the park said the woman had been pushing the child for hours. The mother, Richardson said, had been seen near the same swing set, pushing the boy, since the previous day.
"She was seen there (yesterday), and we don't know if she ever left," Richardson said.
The deputy wanted to start performing CPR, but realized the child had been dead for hours.
"It was really difficult for the officer to encounter the situation," Richardson said.
There were no obvious signs of trauma on the child, who was taken to the medical examiner to determine a cause of death.
The mother was also taken to a nearby hospital to be evaluated, Richardson said.
She talked briefly with authorities, Richardson said, but declined to offer details.
Two GoFundMe pages have been set up by the boy's family members to pay for his funeral. They identified the boy as Ji-Aire Lee, and one described his father's lost custody battle as a failure of the court system. The boy's mother had been struggling for the last several month with mental health issues and homelessness, the other said.
The woman's mother also told WUSA that her daughter had been suffering from a mental illness recently, but she didn't believe she would ever harm the boy. The family had also been homeless, she told WUSA.
The case is being handled as a death investigation, and the woman has not been arrested.
"It's a very sad situation," Richardson said.