This nationwide study examined legal outcomes and possible psychiatric diagnoses of suspected cases of neonaticide. Neonaticide is commonly defined as the killing of a newborn on the day of its birth, and is considered to have not only a low prevalence but also a high level of concealed criminality. This hidden nature guided us to find out what the final legal outcomes of suspected neonaticide were. It was a comprehensive, retrospective, register-based study of all 44 cases of suspected neonaticide that occurred 1980-2000 as recorded by Statistics Finland. The 44 cases were ascribed to 40 suspects, three of whom died themselves during the offence. Twelve cases (27%) were eventually prosecuted and the accused convicted of neonaticide. Their mean sentence was 617 days (SD 216, range 300-1095 days). Fourteen offenders (35% of offenders) underwent a forensic psychiatric examination, out of which four (29%) were diagnosed with a psychotic disorder and 10 (71%) with a personality disorder. Six of the 14 women were not sentenced as criminally irresponsible and three of them were committed to involuntary hospital care. Nine cases (20% of cases) were still unsolved, and in eight (18%) cases the offence title had changed into something other than neonaticide. We concluded that since only 41% of suspected neonaticides completed the court process as neonaticides, the previous results from studies on neonaticide may present a subgroup of offenders, not the whole picture. Therefore, further discussion and research is needed to elucidate this perplexing, sad, and utterly redundant offence in modern society, to prevent it, and develop treatment programs for the offenders.