I ended up creating a train of suspects 1-10 seconds apart throughout the map. I didn't plan it that way but it worked out despite them getting stuck constantly. Started at the main entrance which is my preference for this map. Ended with exactly 15 suspects left because the team kept accidentally arresting some despite trying to hold. I closed all the weapon caches rather than trying to keep 1 open, it just happened that way. Glad this shit is over.

Some tips:
Use Hold command as soon as they walk through a doorway and start shooting suspects.

Never ever turn your back on an enemy that has a weapon on the ground or waistband.

You can take their holstered weapon by canceling the arrest animation.

You can cancel an AI teammate arresting suspect if you're quick enough. Take over the arrest yourself when they start grabbing the suspect, then just cancel yours.

Never call your team to Fall In. If a suspect is in their path, they might arrest them. Watch where they are walking.