It means the indictment on which they were arraigned on are preceded by yet ANOTHER indictment(s) that could take precedence due to date and/or severity. Example:
Prosecuting team 1 says "I got 'em on trafficking". Prosecuting team 2 might say "I have/had an indictment on "Murder, connections to larger groups, etc..". Team 1 might let Team 2 take their case to the courts (if, say, it's a slam dunk), get the accused jailed for the rest of their natural lives, and THEN Team 1 will step in while they are in jail and crucify the fuckers with a ton of other shit.
If they can prove it's all related, you might see Team 1 and Team 2 join forced and create Voltron on their sore asses.