"I'm telling you the truth! I'm no one, all I have is a pet dog! I... wasn't on the roof to sleep, I saw you guys come in here and followed you to listen to what you were talking about, but I won't tell no one if you just let me go!"
"Because... because I can be useful to you! I'm sneaky, I can get into places!" Sosternuto said, drops of sweat(faked, of course) running down his face. Let them think he was good and scared.
Sosternuto grimaced. "Ouch! You don't have to squeeze so hard! In answer to your question, yes. I was sleeping up here because it was the best place I could find and 'your friend here' attacked me! Naturally, I defended myself."
Sosternuto struggled, but obviously this person was stronger and more skilled than he. He let his movements lapse, hoping to get the jump on this person. They'd probably see his face, but that was a small price to pay to get away.