MEXICO CITY – Mexican officials insisted Tuesday that the northern state of Tamaulipas has not fallen under criminal control, but they provided few new details into horrific mass killings and abductions just across the U.S. border.

Investigators increased to 183 the number of bodies recovered from 40 sites around San Fernando, a farming town 90 minutes south of Brownsville, Texas, that a cell of the Zetas drug gang is accused of converting into a giant cartel burial ground.

Marisela Morales, Mexico’s top prosecutor, and federal police spokesman Alejandro Poire, read a statement but did not take questions from reporters. Nor did they provide insight into why the criminals murdered so many people, including scores of bus passengers likely en route to the United States.

Many of the corpses bear signs of devastating cranial trauma, and a sledgehammer found at the scene is thought to have been used in the slayings. Officials said their investigation is ongoing.

“We have doubled our patrols,” Poire said, adding that military authorities and federal police are looking for more suspects.

“The Mexican government is in control of Tamaulipas,” Poire said.