Argentine forensics experts said Tuesday they have started excavating paupers' graves in southern Mexico that are believed to contain the bodies of migrants who died but were never identified.

Team member Mercedes Doretti said the group expects to find about 80 bodies dating back from two months to 12 years ago. The bodies were found without identification near roadways or railway tracks, on a route popular among Central American migrants trying to reach the United States.

Over the years, authorities collected the bodies and buried them in common graves in the cemetery in Tapachula, near Mexico's border with Guatemala.

Most migrants who cross Mexico are from Central America. They frequently suffer assault, kidnapping, robbery and death as they try to reach the United States.

The Argentine Forensic Anthropology Team hopes to extract DNA from the bodies to try to find matches with relatives of missing migrants.

"There are families who have been waiting years for an answer" on the fate of missing relatives, Doretti said.

Doretti said Tuesday there should be no problem extracting DNA, but the process could take two or three months. The experts, including forensic medical examiners, forensic anthropologists and archaeologists, began digging Monday.

They requested permission to excavate from the Chiapas state prosecutors office to work on the project in conjunction with non-governmental organizations. The team has traveled to other Central American nations, aiming to build databases by interviewing the relatives of the missing and taking DNA samples from them that can be used to look for matches.

Previously, a delegation of forensic experts came to Mexico in 2006 to unearth and identify the remains of murdered women found in the border city of Ciudad Juarez. The team has also exhumed bodies of people "disappeared" during dictatorships and victims in countries afflicted by civil wars.

Amid violence against migrants and among drug gangs, Mexico faces a huge backlog in identifying bodies. Nearly 16,000 bodies found in Mexico since 2000 remain unidentified, according to the National Human Rights Commission, an independent government agency.

While the Argentine team has been working for almost 30 years in its homeland, and about 26 years in countries around the world, this is the first time it has exhumed migrants' remains in Mexico.