These stories should be accompanied by whatever the journalist was researching that made them a target. I've never heard of Roberto Toledo until now, and my only knowledge of him shouldn't be that he's dead. Searching his name says that he was a cameraman and his employer was "reporting on corrupt administration and corrupt officials" but surely this is the time to be specific.
Perhaps they simply don't dare to be more specific ...
U.S. journalists don’t have the courage to do journalism anymore. They wouldn’t dare go against the grain, let alone be specific on corruption.
Mexican journalists should migrate, and report on both U.S. and Mexican government corruption without the threat of overt assassination.