<span>1. To attend on the grand juries, advise them in relation to matters of law, and examine and swear witnesses before them.
2. To draw up all indictments and to prosecute all indictable offenses.
3.To prosecute and defend any civil action in the circuit court in the prosecution or defense of which the state is interested.
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https://definitions.uslegal.com/d/district-attorney/
Explanation:
Because it was the first big group of people who had one leader, always lived in a concrete place. Also they invented lots of new things that was more complex than those things who were invented before