Objective: Homicides by older people are rare and might differ from those committed by younger people. To investigate the characteristics of older homicide offenders in New South Wales (NSW), Australia. Methods: A systematic search of legal, criminological and media databases for cases of homicide committed by people in NSW aged 55 and over, during the 18 years from 1993 to 2010. Results: Eighty-seven cases were identified through databases. Legal documents were obtained for 70 offenders, comprising about 5% of homicides committed in NSW in the period of the study. The proportions of male offenders and rates of firearm use were similar to other age groups. Twelve of the 14 homicides using guns occurred outside the metropolitan area. Older offenders were more likely to have cognitive impairment or psychotic illness. Victims were more likely to be female and in a domestic relationship with the offender. Conclusions: Homicide by an older person is rare, and more commonly involves a man killing a family member. Correctional facilities will increasingly have to consider the needs of older people serving long sentences.