Uvalde city officials are using a legal loophole and several other broad exemptions in Texas to prevent the release of police records related to last month's mass shooting that left 19 children and two teachers dead, according to a letter obtained by NPR. Since the May 24 shooting at Robb Elementary School, law enforcement officials have provided little and conflicting information, amid mounting public pressure for transparency. The Texas Department of Public Safety, which is leading the state investigation, previously said that some accounts of the events were preliminary and may change as more witnesses are interviewed. The City of Uvalde has hired a private law firm to make its case, which cited the "dead suspect loophole," to deny the release of information because the gunman died in police custody. The legal exception bars the public disclosure of information pertaining to crimes in which no one has been convicted. The Texas Attorney General's Office has ruled that the exception applies when a suspect is dead. The maneuver has been used repeatedly by Texas law enforcement agencies to claim they're not required to turn over the requested information because a criminal case is still pending, even though the suspect is dead. The loophole was established in the 1990s to protect people who were wrongfully accused or whose cases were dismissed, said Kelley Shannon, executive director of the Freedom of Information Foundation of Texas. "It is meant to protect the innocent," Shannon said.