Complex sentence: Indigenous Australians commit crimes and are imprisoned at a disproportionately high rate in Australia--according to one source, there is "gross overrepresentation of Indigenous offenders at all stages of the criminal justice system".
Split into simpler sentences: Indigenous Australians commit crimes and are imprisoned at a disproportionately high rate in Australia. According to one source, there is "gross overrepresentation of Indigenous offenders at all stages of the criminal justice system".