Killing should be the last resort and should only be justified when the your life is under sever danger. In the case of the OP this wasn't the case, yeah she got robbed and that's bad and yeah they should be punished for their actions but downright killing for it, NO.
OT: Yeah , it was 8:00 pm and we were on Cochabamba halfway to Santa Cruz when a group of robbers stopped the car and demanded all of the jewerly then they left and run to the hills where we lost sight of them.