A life sentence in Australia is the most severe penalty and typically refers to imprisonment for the remainder of an offender's natural life. However, it is usually subject to a minimum non-parole period, meaning the offender must serve a set number of years before becoming eligible for parole, although parole is not guaranteed. The non-parole period varies by state and the severity of the crime, typically ranging from 10 to 25 years. For particularly heinous crimes, courts may impose life without parole. In New South Wales specifically, a life sentence often means imprisonment for the rest of the person's natural life unless a non-parole period is set. Various factors including prior criminal record and mental health are considered in determining the length and parole eligibility.