When Arnette signs into the evidence room the office states that it was 300 pounds worth of Marijuana. When Arnette speaks to Walker he states it was a cocaine bust and milk sugar was substituted for it in the evidence room.
When questioning the witness it's apparent the trial has started. Charges at this point cannot be dismissed and recharged at a future date because jeopardy has been attached to the court proceeding. o do so would be double jeopardy and unconstitutional.