He eyes that phone. They all look the same so he can't be sure, but there's two options here. And one is significantly worse.

"Did you get that off Caitlyn? Fucking fuck I let you go and... did you kill her?" He asks of the roommate he hasn't seen in over a month and is most assuredly gone. But if he keeps deluding himself maybe that will change!

"Or is it your phone?"

That's definitely the worse option.