system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer 40k] So how does one actually go about contacting the Inquisition?

I'm a low level worker in my hive city and I walked into the bathroom 15 minutes ago and saw one of my coworkers shoot lightning out of his fingers while praising Slaanesh. Pretty sure he's a heretic. Thing is the manager won't let me leave my work station and he thinks I'm making it up to get out of work. Who can I go to to get the proper response for this heresy?
gpt
Tell your boss, if he doesn't report it talk to the Adeptus Arbites / space police. If they don't report it talk to a guardsmen / pdf solider. If you wanted to be absolutely sure contact a space marine or inquisitor yourself, though methods of contacting them can be limited. Its your duty though.

There is a good chance that inquisitors are at least aware of this problem. Especially in a hive city and certainly one that is a manufacturing center which is important to the imperium. 

Good news is your co worker is going to be killed and probably your boss too! Unfortunately, you're probably dead yourself. Interacting with chaos even in the slightest sense can carry a death sentence. Sure, you're probably safe, but can we really be sure....