AUSTIN, Texas (AP) — Texas state police officers separated migrant families along the border with Mexico by detaining fathers on trespassing charges and turning over mothers and children to federal officials, the state Department of Public Safety said Thursday.

The separations mark a shift from previous comments by Texas state police leaders who said families should stay together and be referred to federal officers. Amrutha Jindal, chief defender for Operation Lone Star Indigent Defense, told The Associated Press that based on the cases her organisation has seen, the number of family separations may be closer to 40 or more. She said exact data does not exist and their estimates are based on cases encountered by their attorneys.

Jindal said they have identified separations in Maverick County — which encompasses the border town of Eagle Pass — over the last month.

Jindal said her organisation is unclear how distinctions are being made on who is part of a family unit. She said attorneys her organisation appointed to Operation Lone Star clients noticed the issue when they began hearing concerns from clients who didn’t know where their relatives were.

“Some were told that they would reunite with their wife and child,” Jindal said. “Of course, that didn’t happen. They were instead taken to a prison. Others were told they would never see their wife and child again.”

Travis Considine, spokesman for the Department of Public Safety, said in a statement that children have never been separated from their mothers, but “there have been instances in which DPS has arrested male migrants on state charges who were with their family when the alleged crime occurred.”

Governor Greg Abbott’s office referred questions to Department of Public Safety officials, who did not respond to additional requests for comment, including how many families have been separated, when they began and where the detained men are being taken.

The US Department of Homeland Security said Thursday that reports of separated families were troubling and should be investigated. “Managing our border in a safe and humane way works best when we all work together to respect the dignity of every human being and keep our communities safe,” the department said.

Kristin Etter, an attorney with Texas RioGrande Legal Aid, told Hearst Newspapers— who first reported the separations— that she knew of 26 families who had been separated by Texas officials and called the move “nothing short of state-sponsored family separation.” Texas RioGrande Legal Aid did not immediately respond to requests for comment.

Texas’ latest move to secure the border without coordinating with the federal government drew widespread criticism from immigration advocates and some comparisons to Trump-era family separations, though they are markedly different. The Trump administration split thousands of children from all parents who were with them, assigned them to shelters, and struggled mightily to reunite them.

According to an April US Customs and Border Protection memo reviewed by The Associated Press, guidance from the Department of Homeland Security to the agency states a goal to “maintain the unity of family groups” to the greatest extent possible.

But, Jennifer Babaie, director of advocacy and legal services at Las Americas Immigrant Advocacy Group in El Paso, said that she sees cases of family separation through the federal immigration system almost weekly. She said in many cases, people are told they won’t be separated or will see each other soon and then detained separately, making knowing the whereabouts of the other near impossible until they are released from detention or deported.