Romechia Simms, 24, suffers from mental illness, according to the boy's father

The mother who was found pushing her dead toddler in a swing at a Maryland park has been charged with manslaughter, child abuse and neglect of a minor, according to documents obtained by PEOPLE.

A medical examiner previously determined that 3-year-old Ji’Aire Donnell Lee died of dehydration and low body temperature. His death was ruled a homicide.

Police say that his mother, 24-year-old Romechia Simms, put the boy in the swing on May 20 and stayed there with him until May 22, until a concerned neighbor called the police to report a woman who had been pushing a child in a swing for an unusually long period of time.

Family members claim that Simms suffers from mental illness. The boy’s father, James Lee, said he warned a judge about Simms’ possible mental illness and sought sole custody of his son, but his request was denied.

“[The judge] deemed her, at that moment, a fit parent,” Lee said. “I’m not saying she isn’t, but in this situation, he just didn’t pay attention to the signs.”

Simms’ mother, Vontasha, has previously insisted that her daughter is innocent. “[Romechia] would never harm my grandson in any type of way,” she told WUSA earlier this summer. “You know, I just believe she had some type of mental illness, some type of mental break that came upon her where she wasn’t able to get herself out of that situation.”

The evening of May 21 was “rather chilly and it drizzled all night,” Charles County sheriff’s office spokeswoman Diane Richardson said in May.

Simms was arrested on Saturday and arraigned Monday morning. She has not yet entered a plea.

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