As investigative journalist and Irish author Tim MacGabhann reported on the drug cartels in Mexico, he was also supporting them through his own drug use. The experience helped inspire his debut novel, writes Marjorie Brennan

With an investigation barely under way, Mexican journalist protection groups are already expressing fears that authorities will not consider the brutal killing of a photojournalist as being related to his work — even though he fled the state he covered fearing for his safety.