Investigators in Mexico say they are now certain that 43 college students missing since September were killed and incinerated after they were seized by police in southern Guerrero state.br br The attorney general on Tuesday cited confessions and forensic evidence from an area near a garbage dump where the September 26 crime occurred that showed the fuel and temperature of the fire were sufficient to turn 43 bodies into ashes.br br Al Jazeera's Adam Raney reports from Mexico City.