The bodies of at least 50 people was dug out from a grave at a farm outside Mexico’s western city of Guadalajara, local authorities said.
The grim site was discovered just over three weeks ago in Jalisco a state hard-hit by violence linked to organized crime.
The local prosecutor’s office said Saturday 13 of the dead 12 men and a woman have been identified and the remains given to their families.
The process of identifying more of the victims and how they died will continue, it added.
A mass grave with 34 bodies was discovered in a suburb of Guadalajara on September 3, while another was found nearby in May with the remains of 30 people.
Nearly 2,500 murders were reported between January and November in Jalisco where the powerful Jalisco Nueva Generacion cartel is based state authorities have said.