Story highlights Investigators say they've found human remains of 54 victims

Many bodies show signs of being bound, gagged and tortured

They have not yet been identified

Drug cartels operate in the region and are battling for control

Police digging up mass graves in western Mexico have now found human remains from at least 54 victims there.

The grim figure released by Mexico's Attorney General's Office Tuesday was the latest since authorities made the startling find this month of dozens of hidden graves during an investigation into the disappearance of two federal agents.

So far, authorities haven't said whether the missing agents' bodies have turned up in the hidden graves found in La Barca, a town near the border of Mexico's Jalisco and Michoacan states.

Prosecutors say they haven't identified the bodies they've found. Some of the victims showed signs of being bound, gagged and tortured, investigators said this week.

Authorities believe municipal police officers were tied to the federal agents' disappearances, Mexican Attorney General Jesus Murillo Karam said.

"We detained them, and from that investigation, we found a place where the federal agents might have been buried," he said.

For years, authorities have described police corruption in Mexico as one of their top concerns as they combat drug cartels.

Federal officials have said the lower salaries of local police officers make them more susceptible to corruption.

The discovery of the hidden graves comes amid high tensions in the region, where cartels are battling for turf and government forces are cracking down on emerging citizen self-defense groups.