Naman Shrestha
Mario Fierro was a beloved teacher and football coach at a high school in San Diego, California. So, when he was brutally killed outside of his residence in early February 2021, the tragedy sent shockwaves across the entire community. As the detectives delved deep into the homicide, they uncovered some troubling internet searches conducted by a suspect, motivated by jealousy. All the intricate details of the case and the investigation that followed are explored in Oxygen’s ‘A Plan to Kill: Killer Competition,’ which also features exclusive, insightful interviews with Mario’s loved ones and the officials involved in the case.
Mario Fierro Was Ambushed and Killed Outside His Home in San Diego
Born on January 23, 1984, in San Diego, California, Mario Dario Fierro was raised in a seemingly loving household alongside his little sister, Daniella Fierro. In 2002, he graduated from the University of San Diego High School, which later became Cathedral Catholic after relocating to Carmel Valley. In 2016, the committed Catholic landed a job at Cathedral Catholic High School in San Diego, where he served as a social science teacher and football coach. On the personal front, Mario got into a relationship with one of his coworkers at the school, Amy Gembara.
Soon, the couple got engaged in December 2021. Described as a hardworking and compassionate individual, the teacher had a positive impact on many of his students and friends. So, when his life came to an abrupt end around 7 am on the morning of February 1, 2021, outside his home along the 4500 block of Kansas Street in North Park, the tragedy devastated his loved ones. When the authorities arrived at the scene of the crime, they found him deceased on the sidewalk. It was determined that he had died of multiple gunshot wounds. Thus, a homicide investigation was launched immediately.
Mario Fierro’s Fiancée’s Past Came Back to Haunt Him
As part of the investigation, the detectives reviewed surveillance footage of two home security cameras in the nearby area to identify the suspect, who was spotted fleeing in a small, older-model vehicle. Upon delving deeper into Mario’s personal life, they found that his fiancée, Amy Gembara, had been in a relationship with a man named Jesse Milton Alvarez for several years before she began dating Mario. As per reports, on December 31, 2019, she had filed a request for a domestic violence restraining order against Jesse, claiming that he had been stalking her and threatening her life.
It is alleged that Jesse obtained a food service job at her school, but he was sacked on the first day after a security flyer mentioning him was found on campus. The detectives believed that after the suspect learned about Mario and Amy’s engagement through a social media post, Jesse began planning Mario’s murder. According to his internet search history, he conducted searches on several suspicious topics, including hiring a hitman and “how to shoot someone at their home address.” He also managed to locate his ex-girlfriend’s fiancé’s address and staked out his neighborhood.
On the fateful morning of February 1, 2021, Jesse arrived at Mario’s home address and waited for nearly an hour until he exited his home. He then ambushed him from behind and shot him a total of six times. After committing the gruesome crime, he fled the scene immediately. However, armed with enough evidence against him, the police arrested him on the same night in Serra Mesa without incident. Held in the San Diego Central Jail, Jesse was charged with first-degree murder for his involvement in the killing.
Jesse Milton Alvarez is Currently Incarcerated at a California Prison Facility
About three years after his arrest, around March 2024, Jesse Milton Alvarez stood trial for the murder of Mario Fierro. During the trial, the prosecution claimed that the defendant killed Mario due to jealousy over his engagement to his ex-girlfriend. Meanwhile, the defense argued that he shot Mario in self-defense. The accused took the stand and testified that he had gone over to Mario’s house on the morning of February 1, 2021, to talk to him about Amy. He claimed that when he introduced himself to Mario, the latter allegedly began attacking him. Jesse told the jury that he pulled out the gun in self-defense and asked Mario to stop punching him. As per his accounts, the men then began struggling for the gun, leading to Jesse firing multiple rounds at Mario, allegedly feeling scared for his safety.
The defense also claimed that Jesse’s alleged undiagnosed autism led to his obsession with Amy Gembara. In response to the suspicious internet searches he made, he admitted to having fantasized about killing Mario but maintained that the searches were just his way of venting out his emotions and anger over the situation. Ultimately, he was found guilty of first-degree murder, in addition to a special circumstance allegation of lying in wait. On February 5, 2025, during Jesse’s sentencing hearing, Mario’s sister, Daniella Fierro, took the stand and stated, “I experienced a wake for the first time when I saw Mario’s embalmed and mutilated body. Therapy bills. I transitioned from being on antidepressants to taking a drug cocktail.”
She added, “I do believe that actions have consequences no matter how small. I have faith that this court will impart sentencing to Jesse Alvarez, the killer of my brother, that is fair and just.” Mario’s fiancée and the killer’s ex-girlfriend, Amy Gembara, also stated, “Mario Fierro was my beloved fiancé who was maliciously murdered by Jesse Alvarez. One moment, we were planning our wedding; the next, we were planning his funeral. He took Mario’s life but could never erase Mario’s memories and positive impact.” In the end, Jesse was sentenced to life in prison without the possibility of parole, plus 25 years to life. As of today, the 35-year-old killer is serving his sentence at Richard J. Donovan Correctional Facility in San Diego, California.
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