SANDY SPRINGS, GA. (WCMH/AP) – A woman sought for murder in the death of her 9-month-old grandson has been arrested outside Atlanta. Police believe she killed the baby by forcing methamphetamine into his body.

Local news media say 45-year-old Tonya Monroe has a history of drug abuse, and the baby had been born with brain damage. His parents, Taylor and Hayden Shaw, thought he died in his sleep.

“She had walked in,” Taylor told NBC affiliate WXIA-TV. “She walked over to his crib and she said, ‘He’s blue, Taylor, he’s blue!’ So I automatically jumped out of bed, ran over… and I looked down and automatically ran away, screaming and crying, ‘No!'”

Then, the Fulton County Medical Examiner’s Office found methamphetamine in his system.

“Toxicology results came back positive for methamphetamine,” said Sandy Spring Police Captain Mike Lindstrom. “Something that should not have been in a 9-month-old child.”

Detectives believe Monroe intentionally forced meth into the 9-month-old baby to kill him. The motive is unknown.

Taylor Shaw tells WXIA-TV they only agreed to stay with her mother in Sandy Springs because she promised she was clean.

Now Monroe is in the Fulton County Jail on charges of murder, drug possession and cruelty to children. It’s unclear if she has an attorney.