McGowan told her someone else took the boy and left him at the apartment complex at 10300 South Wilcrest.
"She sounded hurt," said Thornton on her phone conversation with McGowan shortly before she turned herself in Thursday.
Thornton said this was the first time she had spoken to her sister in 2022, and that it was their older sister who identified McGowan to the Houston Police Department.
READ MORE: Mother of 1-year-old found abandoned in SW Houston reported missing, police said
"I said (to her on the phone), 'What does not look good right now is that everybody's looking for you and nobody has been able to speak to you,'" Thornton said. "The only thing being released to the public about you is speculation."
McGowan is currently being held on a previous DWI charge, and HPD says the case involving the baby is ongoing.
There have been no charges filed related to that incident.
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As for Thornton, she said her sister's lengthy criminal history has to do with a drug addiction the family has tried to help McGowan conquer.
"I just want the public to know when she's clean, she's a good person," she explained. "She's just made a lot of bad choices. And these drugs, something about them, just pulls her back in."