The guy used a silencer and when his gun jammed he cleared the jam and got off a couple more shots.

that's something you could do with about five minutes of training. if he was a "professional", he probably would've used a nielson device, or, if he just had some shitty turkish oil filter, a non-tilting barrel design, like a hi-point, so the suppressor doesn't induce malfunctions. he also probably would've waited a little bit further down the guy's path. he pulled off his hit in broad view of a camera which was directly behind him, and he stopped for starbucks and a couple protein bars down the street, and left his garbage on site. none of these things matter too much since the police are pretty bad at their job, but if the feds get involved, things might take a different turn, and little mistakes like those add up. if his gun had jammed more severely, he might not have been successful at all. no, this speaks to me as a kind of amateur endeavor.

now, it's still somewhat unlikely, but it is, I suppose, possible, that he was still hired. actual hitmen would probably tend to be so professional that you will basically never see them, like the guy that probably killed the boeing whistleblower, or part of some obviously state sanctioned special forces unit. They can also be unprofessional schmucks that are willing to just eat the sentence for an organized crime syndicate, and in less high profile cases, they can just be random people down on their luck who are willing to kill for a couple thousand dollars and know someone who's willing to pay that fee, which never really works out too well.