A mother whose 6-week-old baby died after being burned, beaten and drugged says she thinks the motive was revenge, a Bogalusa newspaper reports.

The child's mother, Lindsey Daigle, 19, told The Daily News she believes Amy Leighanne Thomas, 22, harmed the baby after finding out that Daigle had tattled on Thomas for taking something from a co-worker's locker.

Daigle doesn't work at the store in question, and she did not tell the newspaper how she learned about the alleged theft.

Thomas denied the allegations in an interview with the newspaper. She said she took the baby to her home and bathed her, but did nothing to hurt the baby.

Investigators have said the infant was beaten on the head, singed with a curling iron and drugged. Thomas was arrested Wednesday, and police said she confessed to the crime.

She initially was charged with second-degree cruelty to a juvenile; after the baby died on Thursday, police said the charge would be increased to first-degree murder.