The 14-month-old boy who died Monday from abusive blows to the head was unconscious from the time he suffered the injuries on the night of March 19 until he died, military investigators said.

The city Medical Examiner’s Office on Tuesday classified the death of Zayden Lonergan as a homicide.

The baby was taken unconscious to the Marine Corps Base Hawaii federal fire station, military officials said. From there, he was taken to Castle Medical Center, where he was found to have skull fractures. Later, he was taken to a care facility in Ewa Beach where he stayed until he was transported to Kapiolani Medical Center for Women & Children on Feb. 23. He died at Kapiolani about 5:05 a.m. Monday.

Marine Corps officials identified the boy as the son of Sgt. David Lonergan, an active-duty Marine stationed at the Marine base at Kaneohe Bay. He is not currently deployed, they said.

Ed Buice, public information officer for the Naval Criminal Investigative Service in Washington, D.C., said: "No one is in custody and no charges have been filed.

"The baby never regained consciousness after the incident last March."

Marine Corps officials said an investigation into the incident was initiated promptly by Marine Corps Base Hawaii. It began as a child abuse/neglect investigation and has been reclassified by NCIS as a homicide case.

The city Medical Examiner’s Office said an autopsy determined that the cause of death was "complications of cranial cerebral injuries due to abusive head trauma," and that the manner of death was homicide.

Marine Corps Base Hawaii "takes very seriously allegations of child neglect and abuse," said a written statement from 1st Lt. Diann Olson, media officer at the Kaneohe Bay base. "Those found responsible will be held accountable."

Honolulu Police Department detectives also investigated the case but have since handed it to the military.