Mexico kidnapping: A twisted moral code explains cartel's apology

Four Americans were kidnapped by a drug cartel, and two of them were murdered, when they visited the town of Matamoros, Mexico. So why would the cartel apologise for the incident and hand over its own gunmen to the police?

A letter left with the cartel gunmen, who had been trussed up and left on the roadside, accused them of acting "under their own decision-making and lack of discipline" as well as supposedly breaking cartel rules over "protecting the lives of the innocent".

It was signed by the "Scorpions Group",...