Of course! I think I've got it!
The Sniper is under the control of Vladmir Von Helson!
Each Victim has a motive now!
Johnny K. Gambino: He was Rivaling the Von Helson Twins. It's possible that the sniper saw that if he shot Gambino, the Tower would Fall. Since the sisters prefered being Socialites over being Vampires, he decided to kill two birds with one stone, wiping out the families Rivals, but at the same time killing the sisters, allowing them to unlock their full potential as vampires.
Edmund's Shooting has an obvious motive as well, he's actively opposing the Von Helsons, so his attack is just to get him out of the way.
But Ian's attack was a snag. I couldn't connect him two the other two victims. That is, until now. Look at the
Story page. Two of the Wallpapers clearly list the name "Von Helson"
Ian's wallpaper does not. It's been said that his last name would be of importance, and he has no other reason to be in a set of Von Helson userbars
unless he is a Von Helson himself!.
The Sniper was trying to kill him, but not out of spite. He was trying to turn him into a vampire!
If what happend to the twins applies, he'd die, then be retrived at a later date, reanimated as a Vampire. I'm guessing Vladmir and Louis have already had this happen. (The Western Wing shows signs of a struggle. It's possible he was murdered there by Vladmir. He then abandoned his family. That's what died twice must mean! He literally died, then he "died" in the eyes of his family.)
So that must mean that the sniper is Vladmir! Or someone related. It would also explain the focus on Durem, and the reason he's cloaked. It's not just to hide his identity (No one would see him anyway), It's to block the sunlight!