The newspaper was given access to a notebook seized by police in the town of San Miguel earlier this year, which reportedly contains details of the income and expenditure of the Fulton Locos Salvatruchos, a clique of the Mara Salvatrucha (MS-13).
The records run from January this year to May, and cover the extortion of taxis as well as local and long distance buses.
Local buses are one of the main sources of extortion revenue, according to the report, which says that the payments on a route generally do not drop below $200 a week, with one route hitting $335 in a single day.
The accounts also show the group's expenses, including taxi fares, food, cell phone credit, and small payouts to relatives of gang members.
InSight Crime Analysis
Extortion has become a highly contentious issue in El Salvador in the light of the current gang truce, in which the Mara Salvatrucha and rival Barrio 18 agreed to cut murders in exchange for concessions from the government. Critics have pointed out that even though killings are down, rates of extortion and other crimes which hurt the civilian population remain high.
The authorities have said that the gangs might make a deal to cut extortion, but the notebook, with its carefully tallied figures, suggests it might be difficult to persuade the gangs to leave behind these earnings, which are their main revenue source. As InSight Crime has suggested, it may be necessary to provide gang members with an alternative income, through large-scale work programs.
However, as La Prensa Grafica points out, the government has said that reports of extortion are down nearly 10 percent for the first nine months of this year, compared to the same period in 2011. El Diario de Hoy reported that in San Miguel, reported extortion cases had dropped from 425 down to 405 so far this year.
However, the newspaper said that this was accompanied by a rise in robberies of people transporting products. Indeed, some reports suggest that while extortion in the name of gangs may be down nationwide, anonymous extortion demands are in fact on the rise.