Forensic workers arrive at the morgue in Iguala Mexico, Sunday Oct. 5, 2014. Mexican forensic experts recovered 28 charred bodies from a clandestine grave on the outskirts of this city where police engaged... (Associated Press) 
 
 IGUALA, Mexico (AP) — A clandestine grave on the outskirts of a Mexican city where police clashed with student protesters a week ago contained 28 bodies but the remains are too damaged for immediate identification, state officials said. 
 
 Guerrero State Prosecutor Inaky Blanco said he could not say whether any of the dead could be some of the 43 college students reported missing after the violent confrontation in Iguala, located about 120 miles (200 kilometers) south of Mexico City. 
 
 He said genetic testing of the remains could take two weeks to two months. 
 
 Blanco said one of the people detained in the case had told investigators that 17 students were taken to the grave site on the outskirts of the Iguala and killed there. But he stressed that investigators had not confirmed the person's story. 
 
 "As long as the identity of the cadavers has not been resolved we will continue the search" for the missing students, he said Sunday. 
 
 State police and prosecutors have been investigating the Iguala city police for misconduct during a series of violent incidents last weekend that resulted in six shooting deaths and more than two dozen people injured. Investigators said video showed police taking away an undetermined number of student protesters. 
 
 Authorities have presented charges against 29 people in the case, including 22 police officers detained soon after the violence. Three of the suspects are fugitives, including Iguala's police chief. 
 
 Blanco said they are still investigating the motive for the crime, adding that some of the police have connections to a local drug cartel. 
 
 Blanco said Saturday that some of those arrested provided key clues that led investigators to the six unmarked burial pits on an isolated hillside about a mile (2 kilometers) from the nearest road. The bodies had been put in the pits on top of branches and tree trunks, which were doused with a flammable substance such as gasoline and set on fire. 
 
 Vidulfo Rosales, a lawyer helping families of the missing students, said relatives of 37 of the young people already had provided DNA samples that will be used to determine if the recovered remains belong to any of the students. 
 
 As investigators worked at the grave site, up to 2,000 protesters blocked a main highway in the state capital of Chilpancingo demanding justice. "You took them alive, we want them returned alive," read a huge banner hung across the road linking Mexico City and Acapulco. 
 
 The mother of one of the missing youths said her son, 17-year-old Luis Angel Abarca Carrillo, had enrolled in the Aytozinapa teachers college attended by the missing students in order to get ahead in life and not be a poor farmer like his brothers. 
 
 "But now look what they did to him, he hasn't reappeared," said 60-year-old Margarita Carrillo. 
 
 Mexico's National Human Rights Commission opened its own investigation into the case for possible "serious human rights abuses," such as extrajudicial executions and forced disappearances by Iguala city police. 
 
 The commission said in a statement Sunday that it had warned about the "delicate" situation in Guerrero, a southern state where poverty feeds social unrest and drug gangs clash over territory. 
 
 Anger over the discovery of the graves exploded Saturday night when a group of young people from the Aytozinapa teachers college protested outside the governor's residence in Chilpancingo. They threw Molotov cocktails and overturned a car after state officials told them they would not be allowed to travel to the graves to determine if the bodies are those of their missing classmates. 
 
 Like many other schools in Mexico's "rural teachers college" system, Aytozinapa is known for militant and radical protests. 
 
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 Associated Press writer Maria Verza in Mexico City contributed to this report. ||||| IGUALA Mexico (Reuters) - Authorities have found mass graves with the charred remains of up to 20 people in the restive southern Mexican state of Guerrero, at a time when police are scouring the area for nearly four dozen missing students after a rash of violence. 
 
 The remains were found on a hillside on the outskirts of the town of Iguala in six graves, which were still fresh, a local official said, speaking on condition of anonymity. 
 
 The identities of the dead were not immediately clear, two officials added. 
 
 Guerrero Attorney General Inaky Blanco told reporters in Iguala on Saturday that the remains would be sent to Mexico’s forensic service to determine whether or not the corpses were those of the missing students. 
 
 He declined to say how many graves or corpses had been found. 
 
 “In the next few hours we will determine the cause of death and the number of bodies,” a spokesman for the state attorney general’s office said. 
 
 Iguala is about 120 miles (193 km) south of Mexico City in the increasingly violent state of Guerrero, the site of clashes involving students, police and armed men last week. At least six people were killed in a spate of incidents. 
 
 Guerrero Governor Angel Aguirre said earlier this week that photos showed police had taken some of the students away. 
 
 Several hundred students protested on Saturday night in front of Aguirre’s residence in the state capital of Chilpancingo, expressing anger that some of their classmates may be among the bodies found in the graves. 
 
 A car was overturned and several petrol bombs were hurled at the residence perimeter, where security outposts were lightly damaged. 
 
 An police official said on Saturday that there was video footage of eight to 10 students being put into police trucks earlier in the week. 
 
 Twenty-two police officers were arrested in Guerrero on Sunday, accused of killing two students during the clashes last week. 
 
 Aguirre said on Saturday that a total of 30 individuals have now been detained in connection with the incidents. 
 
 Slideshow (5 Images) 
 
 Local government officials criticized the police for showing an excessive use of force with the students in Guerrero, where gangs have evolved from a fragmented drug cartel and are fighting turf wars. 
 
 Thirteen of an original group of 57 missing people re-emerged this week. Some had hidden, others had gone home. Dozens are still unaccounted for. 
 
 Many mass graves have been found across Mexico in recent years and months, the legacy of drug gang violence that has killed around 100,000 people since 2007. ||||| Image copyright Reuters Image caption The new graves were found in a village outside Iguala 
 
 Four more mass graves have been found near the southern Mexican town of Iguala, where 43 students went missing last month, officials say. 
 
 There is no word on the number of the bodies discovered in pits on Thursday. 
 
 The discovery came during a huge operation to find the students, who disappeared after clashing with police. 
 
 They were last seen being bundled into vehicles. Last week 28 burnt bodies were found in six shallow graves, but have yet not been identified. 
 
 Forensic tests are expected to take weeks. 
 
 Federal Attorney General Jesus Murillo Karam said the new graves also contained burnt bodies and are in the same area as the first set of graves. 
 
 He said the security operation in Iguala, in Guerrero state, had resulted in the arrest of 34 people - mostly local police. 
 
 He said a formal search had now been launched for the town Mayor, Jose Luis Abarca Velazquez, as well as his wife and head of security. They went on leave after the clashes and have not appeared. 
 
 Media playback is unsupported on your device Media caption The mass graves are overwhelming, reports Juan Carlos Perez Salazar 
 
 The students were holding a protest over hiring practices when they clashed with police on 27 September. 
 
 A number of theories about the reasons for their disappearance have been put forward. 
 
 The students all went to a local teacher training college with a history of left-wing activism, but it is not clear whether they were targeted for their political beliefs. 
 
 Some think that they may have angered a local drug gang called Guerreros Unidos by refusing to pay extortion money. 
 
 Others believe there may be a link between the students' disappearance and a speech given by the wife of Iguala's mayor on the day of the clashes. 
 
 She was speaking to local dignitaries in Iguala on the day the incident occurred and some believe the students may have been targeted because it was feared they could disrupt the event.
– Investigators are still trying to identify 28 "savagely slaughtered" bodies found in mass graves outside the Mexican city of Iguala—but they fear they have found evidence of an atrocity carried out by local police with ties to organized crime. Six students were killed when a group of students clashed with police in the city in Guerrero state late last month, and DNA tests will be carried out on the badly burned bodies that have been recovered to discover whether they are among the 43 students, mostly men in their early 20s, who went missing after the incident, reports the Los Angeles Times. The state's chief prosecutor says it could take up to two weeks to identify the bodies found in the graves, which were found after an anonymous tip. Some 22 local police officers are among more than 30 people who have been arrested over the incident, and the city's mayor and police chief are now fugitives, the BBC reports. The teachers' college the students attended is known for militant protests, and the discovery of the graves sparked a huge protest in the state capital from parents and around 2,000 supporters, who put a huge banner saying, "You took them alive, we want them returned alive" over the highway linking Mexico City and Acapulco, reports the AP.