Staff Sgt. Alonzo Alcantara, a Marine small arms repair technician and former recruiter, has been sentenced to 26 years in military prison for killing his wife, Ruby Tenorio Alcantara, at their home on Marine Corps Base Hawaii in September 2024.
Alcantara pleaded guilty under a deal that reduced a potential life sentence, admitting he used a rear naked chokehold — a martial arts technique he learned during Marine training — to strangle his wife during a violent argument. The couple’s 8-year-old son witnessed the attack, while their younger daughter was also in the home.
Military court documents show that Alcantara was convicted under Article 128b (Aggravated Assault) and Article 131b (Obstruction of Justice) of the Uniform Code of Military Justice (UCMJ) following a General Court-Martial held at Marine Corps Base Hawaii. His case was overseen by Marine judges Catto, Hinson, and Casey, with proceedings taking place in Kaneohe Bay.
At his court-martial hearing in Honolulu, Alcantara stood emotionless as Ruby’s sisters delivered their victim impact statements. “No amount of time will make it hurt less,” said Carolina Jerome, while another sister, Monica, told Hawaii News Now she didn’t believe his apology was sincere.
Monica described her sister as “witty, funny, and a great mom.” But the autopsy painted a brutal picture: Ruby suffered broken ribs, multiple bruises, and blunt force trauma in addition to the fatal strangulation.
Despite those injuries, Alcantara downplayed the attack before the judge, claiming his wife pushed him and that he applied the chokehold to “protect himself.”
During the hearing, prosecutors revealed a disturbing backstory. A year before Ruby’s death, Alcantara had been arrested for child sex crimes after sending explicit messages on the Whisper app to someone he believed was a 15-year-old girl. The “teen” was actually a federal agent conducting a sting operation.
He was charged with child enticement and attempted sexual assault of a minor. Ruby learned of the arrest only after it became public and never told her family. According to Alcantara’s testimony, he used the couple’s savings to hire a private attorney to fight the charges — straining their finances and marriage in the months before the murder.
“She had just turned 38,” Monica said. “She didn’t get to meet my son.”
Monica believes the Marine Corps should have confined Alcantara after his sex-crime arrest to prevent what happened next. “If he’d just been confined, this wouldn’t have happened,” she said. “It definitely played a role.”
Legal experts say Alcantara’s case exposes a troubling gap in how the military handles service members accused of serious crimes.
Under military law, there is no standard bail system, and pre-trial confinement is rare unless prosecutors can prove a defendant is a flight risk, likely to disobey orders, or may re-offend.
Former prosecutor Kevin O’Grady explained that commanders can only order pre-trial confinement if those strict conditions are met. Retired federal public defender Alexander Silvert noted that, in civilian court, Alcantara would likely have been detained briefly for a mental health and safety assessment.
“When it comes out of the blue and somebody’s really ashamed, that’s when something might potentially happen if they’re released,” Silvert said.
Before his transfer to Hawaii, Alcantara had served as a Marine recruiter in Laredo, Texas, where his social media portrayed him as a proud leader and mentor. On Instagram, under the handle @ssgtalonzo, he described himself as a “United States Marine, small arms technician, and mentor” — posts filled with hashtags about leadership, teamwork, and fitness.
That image unraveled as his secret life came to light — a career Marine with an emerging record of violence and deception, whose criminal behavior ultimately destroyed his family.
Following the sentencing, NCIS Acting Special Agent in Charge Oliver Scammell issued a statement acknowledging the devastation left behind:
“Justice has been served, although there are no winners in this tragic case as two young children are now without their mother, and a family has lost a daughter and a sister.”
Alcantara will serve his 26-year sentence at Fort Leavenworth, the U.S. military’s maximum-security prison.
“Ruby dedicated her life to her children, and she was very active with them. She loved baking, tie-dying, and hiking with her children,” her obituary reads. “She leaves behind two children, Alonzo, age 8, and Aracelie, age 5…”
“Without Ruby, there is a void deep inside all of her family that can never be filled. She is and will always be terribly missed. Her sudden and tragic death leaves everyone devastated and heartbroken. Ruby will always be remembered and loved by her family.”
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