SAN JOSE — A Marine lance corporal who said he had an aversion to killing and participating in war will be released by the military, after a federal judge declared him a conscientious objector.

The Marine Corps Reserves must discharge Robert Zabala, 23, by mid-April, according to a 21-page ruling Thursday by U.S. District Judge James Ware.

Corporal Zabala, a recent graduate from the University of California, Santa Cruz, said he was troubled during boot camp in 2003 when a fellow recruit committed suicide and a superior used profanities to belittle the recruit. Corporal Zabala said he was “abhorred by the blood lust [the superior] seemed to possess,” according to a 2006 court petition for conscientious-objector status.

In another incident at boot camp, an instructor showed recruits a “motivational clip” showing Iraqi corpses, explosions, gunfights, and rockets set to a heavy metal song that included the lyrics, “Let the bodies hit the floor,” he recalled in the petition. Corporal Zabala said he cried, while other recruits nodded their heads in time with the beat and smiled.

“The sanctity of life that formed the moral center of petitioner’s life was being challenged,” his attorney, Stephen Collier, wrote in a court filing.

Corporal Zabala, who followed some Buddhist-related traditions but was not a practicing Buddhist, previously applied in June 2004 for conscientious-objector status, but was denied, court records show.

Many of Corporal Zabala’s family members have served in the armed forces, including his grandfather, his parents, uncles, and two cousins.