One of the alleged perpetrators of the presumed killing of 43 students in Mexico has been arrested, the authorities said Friday. The man - an alleged hit man for the gang Guerreros Unidos - was arrested in a joint police and Army raid in Jiutepec in the Mexican state of Morelos early Friday and was being questioned, dpa quoted the Attorney General's Office as saying. Mexican authorities believe that the 43 students from a teacher-training college in Ayotzinapa, in the state of Guerrero, were killed after local police in Iguala, 200 kilometers south of Mexico City, chased and arrested them on September 26. According to suspects who have been arrested in connection with the case, the students were then handed over to the criminal gang Guerreros Unidos. They were then murdered by the gang members, who burned the bodies and threw the ashes into a river in the belief that the students were members of a rival gang. Only one set of remains has been identified. The whereabouts and identity of the remains of the others are being investigated. Authorities say it would be almost impossible to identify any other charred remains that may turn up.