Brian O’Callaghan fought in Iraq, mastered Arabic and became a division chief at the National Security Agency. Last year, wanting a second child for their young family, he and his wife adopted a 3-year-old boy from South Korea.

“He was so loving of him,” a family member said.

It is a background that made allegations revealed in Montgomery County District Court on Tuesday seem all the more stunning: Alone with the boy — with his wife out of town, his other son in a different part of the house — O’Callaghan repeatedly struck the child, hitting him so hard that the boy died two days later.

“An absolutely horrific crime on an absolutely innocent young victim,” said Assistant State’s Attorney Donna Fenton, listing injuries to the boy’s head, neck and back. “Basically this child was beaten to death from head to toe.”

Based in part on her assertions, Judge William Simmons denied bond for O’Callaghan, who has been charged with first-degree murder and child abuse resulting in death. The hearing was the first in the case, one that O’Callaghan’s attorney said was not what police and prosecutors were making it out to be.

Brian O'Callaghan and his wife, Jennifer O'Callaghan, in a 2013 photo. (Courtesy of family)

“This was a terrible, terrible tragedy — and not a crime,” said the lawyer, Steven McCool.

O’Callaghan’s wife, Jennifer, his parents and his in-laws came to court. “He has the unwavering support of his family,” McCool said. “They know he is incapable of committing the crimes alleged.”

O’Callaghan, 36, said little during the hearing as his image was piped in via a video feed from jail.

He attended the University of Northern Colorado and, by 1997, was serving in the Marine Reserve, according to McCool and military officials. He served in Kosovo. In 2003, while deployed in Iraq, he earned the Navy and Marine Corps Achievement Medal for his part in a firefight that helped lead to the rescue of captured soldier Jessica Lynch, according to military records and McCool.

At some point, O’Callaghan went to work for the NSA, where he is chief of the Korea Division in the analysis and production section and holds a top-secret intelligence clearance, McCool said.

At home, he and his wife had one son, who is now 7. They worked through Catholic Charities to qualify to adopt a child with special needs — which is how they adopted Hyunsu from Korea in October. The family called him Madoc, an Irish addition to his name.

For three months, Jennifer O’Callaghan was the boy’s primary caretaker, according to police. In January, Brian O’Callaghan went on leave to care for Madoc, while his wife went back to work. On Jan. 31, she went to New Jersey, and he and their sons stayed at their home in Damascus, authorities said.

It is here that the accounts about what happened differ substantially.

According to Fenton, the prosecutor, some time on the night of Jan. 31 or into the next day, O’Callaghan beat Madoc.

From there, O’Callaghan didn’t render aid, Fenton said. Instead, he moved his injured son from a bed to a blanket and cleaned bodily fluids from inside the home — finally taking Madoc to a hospital in Germantown. The child was in full arrest, Fenton said.

The boy died Feb. 3, police said. An autopsy confirmed injuries consistent with being beaten, Fenton said. Among them: a fracture at the base of skull, bruises to the forehead, swelling of the brain and wounds to other parts of the body. There was also “blunt impact to the back from a linear and triangular shaped object,” Fenton said in court.

Detectives questioned O’Callaghan. He said that on the evening of Jan. 31, he helped Hyunsu take a shower because the child didn’t like having water hit him.

“During the shower, Hyunsu was crying and upset,” Detective Mike Carin wrote in court papers, summarizing his conversation with O’Callaghan. “After the shower had ended, Hyunsu slipped in the bathtub, falling backwards. As he fell, he hit his shoulder. Brian consoled him and he went to bed without incident.”

The next day, O’Callaghan took his sons to breakfast, followed by a trip to a swim center, according to Carin’s summary. The three eventually returned home, O’Callaghan told the detectives, and Hyunsu took a nap.

At 4 p.m., O’Callaghan went to check on his younger son and saw pink stains on the bedding and mucus coming from the boy’s nose, Carin wrote. O’Callaghan told detectives that he changed the sheets, returned an hour later to check on the boy and found his condition had worsened. O’Callaghan told the detectives that the boy was unresponsive and that he washed him off in a bathtub, eventually taking him to the hospital. “Brian O’Callaghan could not provide an explanation” for the injuries, Carin wrote.

“These facts are strong, these facts are horrific, and what this man did to this child is murder,” Fenton said in court.

Detectives got a warrant for O’Callaghan’s arrest Feb. 12 but allowed him to attend his son’s memorial service, McCool said.

In court Tuesday, McCool said that medical tests performed at the hospital appear to contradict the autopsy. “There was a full CT scan done of Madoc, and there were no skull fractures,” he said.

William Rose, O’Callaghan’s grandfather, said the memorial service was moving. The pastor reminded mourners that the boy’s organs had gone to save people’s lives.

“I find it impossible to believe,” Rose said of the murder charge, “because he’s worked so hard to get this baby. He was so loving with him. He’s been so wonderful with his other child. I’ve never seen him do anything that would make me believe he is capable of that.”

Jennifer Jenkins contributed to this report.