Congrats on the promo.
You now need to call an underling to your office. Use the PA system and an ominous tone when you do so. When they get there, looking fearful and cowering, simply ask them to sit down. Then rise from behind your desk, with your hands clasped behind your back and walk around to face them. Then facing the poor schlub, sit on the corner of your desk and say "I just wanted to see how long it would take you to get here." Then let loose with an evil cackle and dismiss them.
Nah, what you do is squeeze them for information:
Call them in one by one:
"I know you know who did it."
Employee: Did what?
"Look you want to protect your coworkers, I understand. But I can't help you if you don't help me."
Employee: What are you talking about?
"Okay, I've been where you're sitting. I'll give you till tomorrow to give me the names of the parties involved, and I'll make sure you're not implicated. But you have to keep this under your hat, you hear me? If I find out you've told people, you'll pay the same price at the rest of them"
Wait and see how many bite and come running in and ratting out each other the next morning
