A mother was charged with killing her year-old daughter after police found traces of cocaine in the baby's bottle, a police investigator said Monday.

Daniela Toledo do Prado, 21, brought her daughter Vitoria to a hospital in Taubate, 75 miles west of Sao Paulo, on Saturday night complaining that the child was suffering from convulsions caused by drinking spoiled milk.

The child vomited repeatedly and died of heart failure early Sunday, police investigator Paulo Roberto Rodrigues said.

Doctors found a suspicious white powder on the infant's tongue. The mother claimed the powder was milk but it tested positive for cocaine, Rodrigues said.

Police searched the mother's house and found a hypodermic needle and a bottle hidden behind a shelf in a baby supply bag. The bottle and the needle were found to have traces of cocaine on them.

"In my 26 years in the profession, I have never seen a mother trying to poison her own child," said Rodrigues.

Rodrigues said that Prado did not remember whether she had put cocaine in the bottle, but said that it was possible.

Prado was charged with homicide and could face between 12 and 30 years in prison if convicted.