It's not required in a GJ presentation because a GJ has the ability to ask questions and seek exculpatory information and bring their own information to the table. But when handled and manipulated by a prosecutor, they simply don't exercise that potential. The GJ system is a dinosaur in terms of initiating felony cases and is actually dangerous, as we are seeing. There are only about a third of the states that use indicting GJs to initiate threshold felony cases for this reason. Some states don't even have indicting GJs anymore.
Really facinating. Then the prosecutor/city can't be sued because they used a grand jury. Extremely dangerous situation especially with an ignorant GJ.