Once Casey was sure that the flat was secure enough for the moment he finally let his eyes settle on Oliver. His dark brown eyes didn't hold it's usual warmth to them, but nor were they really all the cold either. There were traces of worry on his brow, but that was all that he really let show right now. If he was not in this uniform right now, he might have allowed himself to show more. But right now, Casey had to be on his game, juggling the need to help his friend out, but also make sure that, for once, justice was done. Or at the very least, not have the blame put on someone innocent. At least he hoped so. If it was one thing that he'd learned it was that anyone was capable of anything, and for once that wasn't just his paranoia creeping back up into his brain. It wasn't that he thought Oliver did do it, it was just that he had to be through so he could say he believed the other man didn't do it without a shadow of a doubt. Because if someone did set this up, then Casey had to be prepared to back this up and go to the wall for Oliver if he had to. He had no idea if this was just a warning, or an actual plot, but he had to prepare for the worst of it.
"No thank you. On duty." Casey replied, almost apologetically, as he noticed the alcohol bottles, and filed that away for the moment. "I'll be back in a moment." he reassured Oliver as he followed the Medi up the stairs bracing himself for what he knew was going to be behind the door. He stood back a bit, as the Medi worked as Casey made notes in his notebook. They took close looks at the marks around the neck and looked for sings of dark magic. Casey hated this part, keeping a neutral face while his insides were churning. He couldn't have said how long that took, but it felt like it took forever. They spoke quietly with each other for a moment and the Medi assured Casey that the body would be taken care of and taken to the morgue and further autopsy would be done. Once Casey saw the Medi and the body gone he went back downstairs and motioned for Oliver to have a seat.
"I need you to tell me everything. How you knew her, what happened between the two of you, and what happened today." Casey spoke calmly and tried to bring out more of the softer side of his personality rather than the full blown Auror side while still trying to be professional about everything.