Law enforcement has identified a letter from a faction of the Mexican drug cartel apologizing for the kidnapping of four U.S. citizens and the killing of two of them, the Associated Press reports. The letter, signed by the Scorpion faction of the Gulf cartel, apologized to the victims and their families—including a Mexican woman who died in the shooting—as well as to the residents of Matamoros, Mexico, where the Americans were kidnapped, according to the AP. The letter also states that the cartel condemns the violence, writing that the individuals responsible for the kidnapping had gone against the cartel’s rule of “respecting the life and well-being of the innocent,” the AP reports. The faction wrote that it has turned over the individuals responsible for the kidnapping to law enforcement, according to the AP. The AP has yet to confirm whether Mexican officials have new suspects in custody following the letter.