Mexico’s federal government should guarantee the rights of migrants in Mexican territory and establish humane policies, Bishop Jose Torres, the Mexican Catholic Church’s spokesman for migration, added in a letter seen by Reuters and addressed to President Andres Manuel Lopez Obrador and other officials. 

Mexican authorities recovered the bodies in the border state of Tamaulipas over the weekend. Many had gunshot wounds and were badly charred. Guatemalan families, who believe relatives migrating northwards are among the victims, have provided DNA samples to confirm their identities. 

“In the name of the highest values of humanity, we ask the federal government for an exhaustive investigation,” said Torres, who oversees 120 shelters for migrants. He said a lack of legal options pushes migrants towards dangerous, clandestine networks. 

Immigration from Central America and Mexico has returned to the forefront of regional policy since U.S. President Joe Biden took office earlier this month vowing to unwind some restrictions imposed by predecessor Donald Trump. 

“One of the contributing factors to this type of tragedy is the implementation of repressive immigration policies and persecution of migrants who only seek better living conditions for themselves and their families,” Torres said. 

Authorities have not established the identity of the victims or the perpetrators. Tamaulipas Governor Francisco Garcia said on Thursday the killings were an “outrage.” 

Every year thousands of Central Americans and Mexicans flee poverty and violence for the safety and economic stability of the United States. Along the dangerous journey, which includes the vast Mexican territory, many fall victim to crime. 

Tamaulipas is a major migration route and site of cartel conflict. 

“It is a priority that the federal government establishes fair, safe and orderly immigration policies,” Torres said. 

Mexico’s Interior Minister Olga Sanchez this week vowed that the case will not go unpunished.