A Marine found dead in his barracks room at Camp Pendleton early Sunday was beaten to death, a spokesman for the investigating agency said Tuesday.

Ed Buice of the Naval Criminal Investigative Service said Lance Cpl. Mario Arias Jr. died from injuries he suffered at the hands of another Marine sometime late Saturday night or shortly after midnight. That Marine then jumped from a third-floor balcony of the barracks and suffered what Buice described as "significant" injuries.

Authorities are refusing to release that Marine's name and rank until charges are filed, Buice said.

"The pace of the investigation depends on his recovery," Buice said during a telephone interview from the agency's headquarters at Quantico, Va.

Arias' death is considered a homicide and the Marine who leaped from the balcony is the sole suspect.

Authorities will not say where he is being treated or give more specifics about his injuries.

At Camp Pendleton, two sources have told the North County Times that the suspect was apparently drinking when he was confronted by Arias about his alcohol use.

The sources say the suspect became enraged, severely beat Arias and then jumped in an apparent suicide attempt.

Investigators were called to the 19-year-old Arias' room near the Mainside area of the base about 1 a.m. Sunday.

When they arrived, they found the 2010 graduate of Canoga Park High School near Los Angeles dead, according to a statement issued Monday.

Arias was an air-crew trainee with Marine Light Attack Helicopter Training Squadron 303, Marine Aircraft Group 39, 3rd Marine Aircraft Wing. He joined the Marine Corps shortly after graduating from high school.

The case is being handled by the Naval Criminal Investigative Service's Major Response Team. The civilian law enforcement agency is responsible for investigating crimes involving Marines and sailors that occur on military bases.