Introduction: Several studies have shown an association between homicide and sexual chromosomal abnormalities. but data are still lacking regarding Klinefelter syndrome. Methods: We retrospectively reviewed two cases of homicide perpetrators who were both diagnosed with Klinefelter syndrome on the basis of a karyotype analysis. A neurocognitive assessment was also performed (MMSE. https://www.roneverhart.com/Doorking-1835-080-Telephone-Entry-System/