text: The rural grave, discovered last November in the town of Tetelcingo, consists of two 10m (33ft) deep pits.
  Prosecutors say that the bodies may have been dumped illegally by morgue officials, but the investigation into who is responsible is ongoing.
  Morelos is among the worst-affected states in Mexico's epidemic of drug-related violence.
  At least 20,000 people have disappeared across Mexico, the UN estimates - other organisation put the number far higher.
  Investigators at Tetelcingo worked under a yellow tent as families of missing persons and National Human Rights Commission representatives looked on.
  Genetic samples will be taken from each set of remains to attempt identification before they are reburied in marked graves.
  The exhumation is expected to take about five days.
  State prosecutor Javier Perez Duron said an investigation was under way into who was responsible for the illegal mass burial.
  "It is extremely important and the highest responsibility to count the bodies and give them a dignified burial," Mr Duron said.
  Experts from the Autonomous University of the state of Morelos (UAEM) have been called in to help with DNA testing.
  Alejandro Vera, rector of UAEM, said: "We recognize the tireless struggle of the relatives and victims' organisations of the more than 30,000 missing in this country that's sinking into barbarism."
  Mr Vera founded a program to help those whose loved ones have disappeared in Mexico's drug war.
  At least 20,000 people are thought to have disappeared.
target: Mexican authorities have begun exhuming 116 bodies found buried in a mass grave in the central state of Morelos.