Investigators have uncovered 13 more bodies in mass graves in the violent northern state of Tamaulipas, where 59 dead were exhumed earlier this week, it emerged today.
Families and authorities from across Mexico contacted the morgue in search of those who have vanished in the country's drug-war.
Seventy-two bodies have now been discovered since authorities began chasing reports in late March that gunmen had kidnapped people off of passenger buses headed toward the US border.
Nine of the bodies were discovered in one newly found grave and four in another yesterday near the city of San Fernando, state Interior Secretary Morelos Canseco said today. The total now matches the number of migrants who died in a massacre near that town last August.
Mr Canseco said investigators are searching for yet more graves in the area.
Families came to the morgue in the border city of Matamoros across from Brownsville, Texas, looking for loved ones not seen for a couple of weeks, others a few months - some as long as three years.
Mr Canseco said he has heard from officials in the central states of Guanajuato and Queretaro searching for residents who disappeared on buses traveling through Tamaulipas or to US border.
Authorities speculate the men pulled off the buses fell victim to ever more brutal recruiting efforts to replenish cartel ranks. But one local politician, who didn't want to be quoted by name for safety reasons, said there were rumors that the Gulf cartel was sending buses of people to fight the Zetas, who control that stretch of road and who began boarding buses in search of their rivals.
Whether the victims found in the pits were innocents caught up in the violence, migrants or drug traffickers executed by rivals, there are many more missing in San Fernando, the politician said, adding "If they keep looking they'll find more and more mass graves."
Guanajuato attorney general spokeswoman Susana Montero said 17 missing people rode an Omnibus de Mexico company bus to northern Mexico in March. The bus route and exact date were unknown, but Ms Montero said they were apparently travelling to the United States.
In the western state of Michoacan, the attorney general's office said it also was working with Tamaulipas to determine if any of the 59 people missing from that state in the last 12 months were killed and buried in northern Mexico.
Mr Canseco told the Milenio television channel that he had yet to hear from other countries, particulary those in Central America, the origin of thousands of migrants who cross Mexico each year on their way to the US.
The victims of the August massacre were from from El Salvador, Honduras, Guatemala, Ecuador and Brazil. Survivors said they were killed for refusing to work for the Zetas drug cartel.
Federal security spokesman Alejandro Poire announced yesterday that 14 suspects linked to the killings had been arrested by Wednesday. Those arrests apparently led authorities to the pits.
The suspects belonged to a "criminal cell," Poire said, but he did not specify which gang they may have belonged to.
State authorities are still not sure about the origin of the victims found in the pits, but suspect at least some had been abducted from buses.