Quem é realmente o atirador?

Não. Jack Reacher não os mata ... ele é o cara legal.

A pessoa que cometeu os assassinatos é "Charlie" (Jai Courtney).

Veja a sinopse da trama aqui :

We cut to a meeting in a dark area between a guy who's been following Reacher, and the actual shooter, whose name is Charlie. We also meet the boss, who is only known as "The Zec" (Werner Herzog). We learn that only one of the victims was intended, and the rest were shot to cover this up. The first goon is being hassled by Charlie and The Zec about his loyalty after they get into an argument, and The Zec reveals that he bit off his fingers at one point to survive frostbite and gangrene. He orders the goon to do the same to prove his loyalty, but he can't, so Charlie shoots him. Charlie asks The Zec what they should do about Reacher, to which he replies "what we always do."

Aqui está uma foto dele do filme:

O atirador foi Charlie interpretado por Jai Courtney e ele fez porque foi contratado e o alvo real era um dona de uma empresa de construção civil, "os bandidos" queriam adquirir sua empresa e não queriam nenhuma suspeita levantada sobre sua morte.

De este

So the big twist in Jack Reacher is essentially that the whole sniper routine was a setup to kill one specific individual, and the other victims were murdered as a distraction, so the police and media would focus exclusively on the killer—who was handed to them in a frame-up.