Allen County Prosecutor Karen Richards said no criminal charges would be filed because of the "false positive" results, The (Fort Wayne) Journal Gazette reported Wednesday.
Among other things, the report indicated the 7-year-old girl had in her system marijuana; methadone, a synthetic opiate used to treat pain and heroin addiction; and PCP, or phencyclidine, an illegal hallucinogenic drug.
A police report indicated the girl was brought to the emergency room Feb. 27. When a Child Services Department representative tried to interview the mother, the mother offered information about a child caregiver who may have had "some responsibility" for exposing the child to the drugs reportedly found in her system, the police report said.
But the test results now appear to have been wrong, hospital and legal officials said.
"There apparently were issues with the accuracy of the test, and the hospital does not believe the tests were accurate," Richards said.
A hospital spokesman confirmed the test produced a "false positive," but declined to comment further, The Gazette Journal said.