Nobody knew that they were coming, but everyone knew when they arrived.
The entire base erupted into chaos, every single mech and femme scattering and praying to Primus or Unicron or whatever higher power might be listening, that the Deception Justice Division isn't there for them.
It had soon become clear however that the D.J.D., while certainly looking for someone, were also cleaving through any mech that fled under the idea that if you're not guilty, you have nothing to hide and thus no reason to run.
They'd found their target soon enough, and Tarn had made sure to broadcast that smooth, low voice of his throughout the entire base, causing everyone's sparks to tighten painfully and all the remaining mechs to double over.
"This, my dear Decepticon brothers and sisters, is what happens to traitors." He'd said, each word lowering in tone as he rambled about the glory of Megatron and the Deception cause with a terrifying kind of zealous fervour until you were sure that your spark was simply going to explode from the pressure, but Tarn had cut the broadcast just before he uttered the final word and killed the traitor.
It was a small mercy, as everyone in the base now needed urgent medical attention, including the medics, and for a moment you were sure that the D.J.D. had done their job and we're now going to be on their merry way.
But then the broadcast started up again, Tarn's voice echoing through the speakers in the halls once more, with faint crackling and dripping sounds in the background.
"Now then, on to the next order of business. Seeing as this traitorous wretch-" There's a sicking wet CLANK sound, "- was such a high ranking Decepticon and you all took orders from her, we need to weed out who exactly was aware these goings on, and who was simply following orders like a good Decepticon should. We wouldn't want to accidentally harm one of our own, after all."
"Stay put, my brothers and sisters. The Decepticon Justice Division will bring each of you in for... Questioning."