Mexico City, Dec 28 (IANS/EFE): Authorities at all levels did a poor job of investigating the August 2010 massacre of 72 undocumented migrants in northeastern Mexico, the country's independent National Human Rights Commission says in a report released Friday.

Police allowed evidence to be lost or compromised, forensic personnel mishandled the bodies of the victims and government agencies were negligent in caring for the two survivors of the bloodbath on a ranch near the US border, the commission said.

The autonomous, publicly funded panel also criticised the Tamaulipas state attorney general's office and the federal AG's office, which ultimately asserted jurisdiction over the case.

Authorities have yet even to identify all of the bodies, the commission noted.

The group of 74 migrants was headed toward the US border Aug 21, 2010, when armed men intercepted their bus and took them to a ranch outside the town of San Fernando, Tamaulipas, according to the survivors' account.

Migrants headed for the US are often targeted by Mexican criminal organisations, which kidnap them or try to forcibly recruit them to join their gangs.

In this case, when the migrants refused to join, their abductors decided to kill them.

One of the two survivors, Ecuadorian teenager Luis Freddy Lala Pomavilla, notified Mexican marines of the killings.

Marines found the bodies of the 58 men and 14 women after a shootout with gunmen at the ranch that left a marine and three criminals dead.

Mexican authorities have blamed the San Fernando massacre on Los Zetas, the country's most violent drug cartel.

The human rights commission urged the federal AG's office to train its investigators and forensic personnel in the legal and scientific protocols for handling and preserving the bodies of crime victims.