Chihuahua chief of police was arrested on charges of murdering 9 women and children of dual US-Mexican nationality last month.

Fidel Alejandro Villegas, police chief of the small town of Janos in Chihuahua state, was arrested by federal authorities on December 27. The role of Villegas is not clear in the attack, but Mexican authorities say he is related to organized crime.

A three-car convoy carrying 17 women and children of dual US and Mexican nationality was shot down by gunmen on November 4 in the state of Sonora, northern Mexico, killing nine people on the spot. Police suspect the culprit is the gunman Juarez, a drug gang that is trying to scramble for territory with Sinaloa gang in Sonora state.

Mexican police took up to 10 hours to be present at the scene of the massacre, said Julian LeBaron, cousin of one of the victims. The LeBaron family believes that the Villegas arrest proves that Mexican law enforcement cooperates with the drug gang.

"They have a monopoly on security, they are paid to protect the people. And then we found out they were involved in the killing of women and children," the LeBaron family told the New York Times.

Mexican and American public opinion both demanded that the authorities bring the attackers to justice. Previous police arrested three suspects. After the massacre, US President Donald Trump declared Mexican drug cartels as terrorist organizations and questioned President Andres Manuel Lopez Obrador's brutal crime-fighting strategy.

Gang violence is a serious problem in Mexico. The number of murders in the country in the first half of this year rose to a record of 14,603, surpassing 13,985 in the same period last year. The total number of murders recorded this year is also likely to be higher than 2018.