It's a serial killer folks. Sure, it's serial killer who has come up with a new twist, but it's still probably a home grown young adult(s) who watches too many movies and has tired of video games.
I hope your take on this is correct. I really do, because eventually that bored, "young adult" will make a mistake and get caught. If you're wrong, all of us are walking around with a bulls-eye on our backsides. This is too slick - a higher level of evil than the neighborhood punk, and it's going to spread.
No, these guys (plural) are not serial killers. They're sending us a sick, twisted little 9/11 message, and I believe the message has been sent, and there will be no more assassinations in this area, at least not for a long while.