"Just had to check," Sirius replied, satisfied with the answer and Roddy's indignant reply. "But at this rave, surely there are some people who can vouch for you?"

The people who hired him are the first that come to Sirius's mind, or anyone else who may have interacted directly with him. Unless that's where the illegal part comes into play.

"It sounds like tracking down this Kyle fellow might be the place to start though."