Article continues below advertisementMartin Short's daughter Katherine's heartbreaking cause of death has been confirmed.The 42-year-old died from a self-inflicted gunshot wound to the head on February 23, according to a death certificate from the Los Angeles County Department of Public Health.The document, which was obtained by TMZ, states Martin's only daughter was cremated on February 27 and "shot herself" at her California home. The death certificate also lists Katherine's occupation as a social work therapist and that she was never married.