The story very much reads like a hit for sure. It sounds like he was interrupted because the neighbor called from hearing the screams and loud noises. I would imagine if he had another hour the body would have left the scene in the man's suitcase and the apartment would have looked spotless.
It surely means it's highly premeditated, but doesn't necessarily mean it's a hitman. The Stephen McDaniel case is an example of a boring-seeming law student showing similar levels of planning when murdering and dismembering a woman he was stalking.
The fact that there were screams loud enough to concern neighbors could suggest it wasn't quite so professional. If it were a professional hitman, why not use something guaranteed to instantly and silently incapacitate him, first, then focus on cleaning up the evidence? Or did they try to, but it didn't go as planned?
One possible explanation would be that the goal was to send a message (to him before his death, and others after it), not to try to make him disappear without a trace. Though, either way, it doesn't necessarily mean it was a professional hitman.
