Presented are the case history and toxicological findings of an infant fatality involving methadone. A mother found her 10-month-old infant unresponsive in a crib. The infant was taken to a hospital; however, she was cold and stiff on arrival and was pronounced dead. Few details regarding the case history were known at the time, and the autopsy findings were unremarkable. Specimens were submitted for a full toxicological analysis, including an alcohol analysis by headspace gas chromatography with flame ionization detection; a screen for drugs of abuse and several prescription drug classes using an enzyme-linked immunosorbent assay technique (ELISA); and a screen for basic compounds using gas chromatography-mass spectrometry (GC-MS). Positive findings were confirmed and quantitated using GC-MS. Methadone was detected in subclavian blood at a concentration of 0.67 mg/L. The cause of death was determined to be "methadone intoxication", and the manner of death was "homicide". A discussion of the case circumstances, the toxicology findings and methadone pharmacokinetics are presented.