CHILPANCINGO, Mexico — Tens of thousands of teachers, activists and residents marched and blocked a major highway in the Guerrero state capital Wednesday to protest the disappearance of 43 teachers college students and demand that authorities find them.
The protesters shut down the highway that links Mexico City with Acapulco, marching behind a banner asking "Who governs Guerrero?" — a reference to the fact that local police working with organized crime have been implicated in the disappearances in the city of Iguala.
"Whose hands are we in?" said Rosa Ruth Rodriguez Mendiola, a housewife from the city of Atoyac who joined in the march in Chilpancingo.
Investigators still had no word on whether the 28 bodies found in a mass grave over the weekend included any of the missing students, who disappeared after two attacks allegedly involving Iguala police in which six people were killed and at least 25 wounded.
The students from the radical rural teachers college had gone to Iguala to solicit donations from passers-by. They were meeting up to return home about the same time the mayor's wife, Maria de los Angeles Pineda, was finishing a speech to local dignitaries downtown.
Javier Monroy, an activist in Chilpancingo for the families of the disappeared, suggested the attack could have been caused by the local gang, Guerreros Unidos, which thought the students were going to disrupt the speech by Pineda, whose relatives have drug gang ties, according to prosecutors.
Federal Attorney General Jesus Murillo Karam has declined to speculate on any link between the speech and the violence.
"I am not going to single out any hypothesis until I have confirmed which is the correct one," he said late Tuesday.
Iguala Mayor Jose Luis Abarca is a fugitive, and state officials have arrested 22 city police officers, who have been replaced temporarily by a special federal police unit.
The whereabouts of the mayor's wife are unknown. In a Sept. 29 interview with Milenio Television, Abarca said he received reports from police that the students had been attacking and robbing people who had come to the speech and dance.
"Don't be provoked," Abarca said he told them. "I don't want any kind of violence ... Leave them alone, they're just passing through."
He said he later received reports of confrontations in different parts of the city throughout the night.
Prosecutors had identified Pineda's late brother, Alberto Pineda, as a main lieutenant in the Beltran Leyva cartel. He and another brother, Marco Pineda, both were on former President Felipe Calderon's most-wanted list and were killed by rivals in 2009.
Another brother, Salomon Pineda, was released from prison last year and is believed to be the Iguala chief for Guerreros Unidos, an offshoot of the Beltran Leyva group, according to local media.
Murillo Karam said there was no hard evidence until now of the couple's involvement in criminal activity.
"We don't investigate on the basis of kinship but rather facts," he said.
The chief prosecutor for Guerrero state, Inaky Blanco, said suspects have testified that as many as 30 members of the Iguala police force were members of the Guerreros Unidos gang.