What police found at her Camden rowhouse early Wednesday was even more horrifying. Thomas had decapitated her son and placed his head in the freezer.
The 33-year-old mother later fatally stabbed herself after hanging up on emergency dispatchers, a violent end to a troubled life.
Thomas only recently regained custody of son Zahree after allegedly leaving the boy unattended in a car, telling police she had smoked marijuana laced with the hallucinogenic drug PCP and blacked out in a nearby park.
Distraught family members who arrived at the scene late Wednesday morning, shocked expressions on their faces, declined to comment. Some neighbors described strange behavior by Thomas, who had just moved to the street from elsewhere in the city. Others saw no evidence of problems.
"Because, had we known something was up, I'm quite sure all the neighbors on this block would have talked to her," said Tayari Horcey, who lives a few doors from Thomas. "But, you know, people hold stuff in. You don't know what's going on."
The state's child welfare agency said in a statement that Thomas had been receiving counseling and support services since a court-ordered reunification with her son April 3.
She previously lost custody of Zahree to relatives and was ordered to undergo treatment for substance abuse and mental health disorders, according to the Department of Children and Families. Thomas was charged with child endangerment in the 2010 car incident, but the case was dropped because of a problem with a witness, said Jason Laughlin, spokesman for the Camden County prosecutor's office.
The gruesome events began unfolding Tuesday night in Camden, an impoverished, high-crime city across the Delaware River from Philadelphia.
Neighbor Melanie Troutman reported seeing Thomas and her boyfriend sitting on the steps of their home, a familiar sight. But Troutman said that on this night, Thomas was topless and "clearly upset." Horcey insisted Thomas was clothed.
About two hours later, Thomas called 911. During the call, she first accused her boyfriend of stabbing Zahree, but then quickly recanted.
"You know what, I did it, I'm lying, I'm lying, I'm lying, I did it," she said, according to a recording of the rambling, often incoherent call released Wednesday evening.
"I did it, I did it, I did it," she repeated later.
When asked if she takes medicine, Thomas said she used to take the antidepressant Prozac.
"I didn't take it today, but I should have," she said.
Police later found Zahree's body on the first floor of his mother's home, then discovered his head in the freezer. A medical examiner found a chest stab wound and marks on the child's arms, Laughlin said.
Thomas stabbed herself in the neck with a kitchen knife shortly after hanging up on dispatchers, Laughlin said.
The Department of Children and Families said its staff had visited with the family regularly and was in communication with all service providers. The agency said it would investigate the deaths of both mother and child.
The department has been under the supervision of a federal judge and undergone a major overhaul since 2003 as a result of high-profile lapses in the oversight of children.
Thelma Moore, a former neighbor, said Thomas had exhibited mental health issues during the several years she'd known her. Moore described her as being in "a world all to herself," and said Thomas had seen a behavioral health therapist.
"She just walked around and talked and cursed to herself," Moore said.
But Thomas' landlord, who did not want to be identified, said the woman had lived at the home for two months and was a perfect tenant, keeping the apartment tidy.
Court records show Thomas faced dozens of judgments and liens filed in civil court in New Jersey dating back to 2002.