In which case you don't know the full facts, have chosen not to share the full facts, or misunderstood what you were told. Nobody would be talking about a minimum of four years in prison for mere cocaine residue.

Perhaps you misunderstood the maximum penalty for simple possession (four years incarceration) as the minimum he's likely to face? If it's not that, the case involved substantially more than cocaine traces, your brother has a significant criminal record, or both.

Tell him to work with a criminal defense lawyer in the county where he was charged.