SAN DIEGO — Mario Fierro was “all in” to his students, his players and his faith.

That’s how colleagues described his approach to life.

Although he died Feb. 1, the victim of a homicide, the beloved teacher and coach lives on in the memories of colleagues and students at Cathedral Catholic High School.

The death rocked San Diego’s Catholic community, particularly high school students and staff members, who struggled to understand the tragedy.

Last December, Fierro had become engaged to one of his fellow teachers at Cathedral Catholic.

The alleged killer, Jesse Alverez, 30, was the ex-boyfriend of Fierro’s fiancé. Alvarez was later arrested and charged with murder. No trial date has been set but the court was to hold a status hearing in the case March 29.

Those who knew the 37-year-old Fierro well paint a portrait of an educator with a tremendous work ethic and an even bigger heart.

“Mario was ‘all in’ on life, and he lived a short life, but he lived a great life,” said Kevin Calkins, Cathedral Catholic’s principal, who hired Fierro as a social studies teacher in 2016.

Head football coach Sean Doyle, whom Fierro served as an assistant coach, said he truly cared about everybody he came in contact with,” and enjoyed life, his teaching and his coaching “to the fullest” and he never did anything “halfway.”

At the start of the school year, Fierro already had a full load of five classes, but that didn’t stop him from volunteering to teach a sixth, Calkins recalled.

If that wasn’t enough, about a month before his death, Fierro offered to pick up another class when it was announced that a colleague was taking an extended, health-related leave of absence.

“That would’ve meant Mario would’ve never had a break during a school day,” Calkins told The Southern Cross, newspaper of the Diocese of San Diego. He had Fierro stick with six classes. “He was willing to teach every single period every single day.”

John Montali, a science teacher and a football coach at Cathedral Catholic, came to know Fierro as “not just a colleague but a friend” and said he was a guy who would “give you the shirt off his back.”

Fierro was fatally shot outside his home, dying at the scene. Being killed in such a violent manner was a sad irony, Montali said, because his late friend was “a peacemaker” by nature. He noted that Fierro had the ability to speak to all sorts of people about subjects like politics, religion and sports — “all of those kinds of topics that tend to raise people’s ire” — in a way that didn’t lead to heated disagreements.

A 2002 graduate of University of San Diego High School, which three years later became the present-day Cathedral Catholic, Fierro was a committed Catholic. His friends noted his affinity for the traditional Latin Mass at St. Anne Church in Logan Heights, California.

In the classroom and at athletic events, he seemed to have boundless energy.

Calkins recalled he was constantly on the move, walking back and forth as he delivered his class lectures.

Fierro served as assistant coach for track and field for about 10 years, until about three years ago, said Dan Geiger, a math teacher and track and field coach at Cathedral Catholic.

He described Fierro as “so into coaching” that when his athletes were running the two-mile at a track meet, “he probably ran close to two miles himself, just running around the track and cheering them on.”

“It was just one of those funny things, watching a coach almost act like a little kid because he was so enthusiastic about the performance of his athletes,” said Geiger, who like Montali had been one of Fierro’s own coaches in high school.

Geiger also recalls how, in 2010, when two recent Cathedral Catholic graduates and former track team members died in an automobile accident, Fierro helped team members process their grief.

In the wake of Fierro’s death, Geiger said he met with that same group of former athletes, “and now they’re dealing with a second tragedy.”

Last April, when defensive lineman and Cathedral Catholic junior Jaxson Moi received his first scholarship offer, Fierro was one of the first people with whom he shared the good news.

Moi recalled that, while Fierro expressed his pride at his achievement, he also “kept it real with me.”

“He told me to always remain humble, never be complacent, and with all the great things that come in your life, always give the glory to God,” he said. “That was just the type of person that Coach Fierro was.”

Grasska is assistant editor of The Southern Cross, newspaper of the Diocese of San Diego.