Isauro Aguirre, also known as Tony, was born on June 13, 1980. He had a challenging early education, repeating two grades before eventually dropping out of school. This led to implications suggesting he may have had a learning disability.

In his early adulthood, Aguirre found work at Woodland Park Retirement Hotel. He served as a caregiver and a driver there. Susan Weisbarth, the executive director of the retirement home, described him as a "quiet, down to earth nice person" who was always willing to help. She noted that during his three years of employment, Aguirre was patient and loving. He often changed diapers of elderly residents and was affectionately nicknamed "Shaggy" by the staff. Another coworker mentioned that while driving residents, Aguirre would take scenic routes so they could enjoy views other than the freeway.

Around a year and a half to two years before taking custody of Gabriel Fernandez, Aguirre met Pearl Fernandez. In October 2012, Aguirre transitioned to a new job as a security guard for AVL Private Security. He worked at Vallarta Market in Palmdale, California, through this security position.

Gabriel Fernandez was an eight-year-old boy who suffered severe abuse and torture. On May 22, 2013, his mother, Pearl Fernandez, called 9-1-1 to report that Gabriel was not breathing. When first responders arrived, they found him naked and covered with injuries. He had been brutally beaten by Pearl and her boyfriend, Isauro Aguirre, after failing to clean up his toys. Aguirre later made a comment suggesting that Gabriel was "gay."

Paramedics rushed Gabriel to Children's Hospital Los Angeles, where he was declared brain dead shortly after arrival. He died two days later, on May 24, 2013. The autopsy showed that Gabriel died from blunt force trauma, which was compounded by neglect and malnutrition.

After the incident, Pearl Fernandez and Isauro Aguirre were arrested. Initially, Pearl was charged with felony child endangerment, and Aguirre was charged with attempted murder. Following Gabriel's death, both faced more severe charges of first-degree murder with special circumstances of torture.

In the trial, prosecutors described the extensive abuse Gabriel endured during the eight months he lived with Pearl and Aguirre. The jury found Aguirre guilty of first-degree murder and torture charges. On December 13, 2017, the jury recommended the death penalty for Aguirre, which was accepted by the judge.

Pearl Fernandez accepted a plea deal, pleading guilty to avoid the death penalty. She received a sentence of life imprisonment without the possibility of parole. Aguirre, however, was sentenced to death and remained in prison awaiting execution. He was admitted to San Quentin State Prison and later transferred to another facility.