A Maryland intelligence official has been arrested for allegedly killing and abusing his 3-year-old adopted son, Montgomery County police said. Brian Patrick O' Callaghan, 36, of Damascus, was the chief of the National Security Agency's Korea division when he was arrested on Feb. 16, officials told CBS News. His son, Hyunsu O' Callaghan, died Feb. 3. A medical examiner ruled that his death was caused by multiple blunt force injuries. Hyunsu was unresponsive when his father took him to the emergency room, and injuries indicated that the boy had recently been beaten, doctors told police. "These types of injuries are consistent with acute head trauma and Brian O'Callaghan could not provide an explanation that would cause this type of medical distress to Hyunsu," documents stated. O'Callaghan told police the child had slipped in the bathtub on Jan. 31 and fell backward, hitting his shoulder. The boy's injuries included a skull fracture with bleeding in the brain, and his body also showed multiple contusions, CBS reported. O'Callaghan is being held without bail. His attorney claimed that the death of the boy was a tragedy, but not a crime. "[O'Callaghan] has the unwavering support of his family, they know he is incapable of committing the crimes alleged," McCool said after the hearing, the Post reports. The boy was adopted from Korea and has been in the United States since October 2013.