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, Tex., 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 killed so many people, including scores of bus passengers probably headed 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. DNA tests to identify victims will take three to four weeks, authorities said.

“We have doubled our patrols,” Poire said, adding that military authorities and federal police are looking for more suspects in addition to the 74 in custody, who include 17 of San Fernando’s 25 police officers.

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

Warring gangsters have carried out several attacks in the state despite the added security. Officials said federal police have rescued 122 kidnapping victims in the past week from three locations in Tamaulipas and arrested several local police officers suspected in the crimes.

On Monday, federal police raided a location in the border city of Reynosa where 51 victims were being held, including 18 Central American migrants and six Chinese nationals. Sixty-eight victims were freed April 19 from another criminal safe house in the city.

Morales said that the kidnappers were demanding $1,000 to $2,000 from the victims’ families and that six Reynosa police officers accused of working for the Gulf Cartel had been arrested.

The grisly findings in Tamaulipas have overshadowed recovery efforts at another mass grave hundreds of miles away, in the city of Durango, where 75 bodies have been found since April 11.