You gotta wonder what other stuff he has done. This sounds way too cold blooded to be a first time thing. I mean it barely seems like he made any attempt to cover up the crime.
Usually with first time kills, it's very sloppy...but because people tend to panic afterwards. They make attempts to cover up the crime, but their nerves make them overlook things. Stupid things. This doesn't look or sound like that at all. Looks like he just wanted to kill the dude, walked away and figured he could just move on.
You're a millionaire! Morals aside, you could have paid someone like $15,000 (maybe less) to do this. Never would have even had a connection to the weapon or the crime scene.