Brother Konrad Diebold led St. Patrick High School for 26 years

Brother Konrad Diebold gave every last ounce he had to St. Patrick High School, an all-boys Catholic school on the Northwest Side.

Over 35 years he served as teacher, principal and president before retiring in 2013 to his residence across the school’s parking lot.

On Monday he answered the call again. A substitute English teacher was needed. It took him back to his roots. He even ate lunch in the cafeteria.

A short time later, Diebold suffered a fatal heart attack and collapsed on the sidewalk outside his home. He was 85.

Dan Santucci, the school’s current president, showed up to work the next day in the outfit everyone wears — khakis and a polo shirt — but found himself underdressed.

“All the kids came in a shirt and tie. They did that on their own to honor him, which is pretty special,” he said.

Before going into education, Santucci was an athlete. He played football for St. Patrick’s and the University of Notre Dame before making it to the NFL.

Diebold was the first to knock on the Santucci family’s door in Harwood Heights, bottle of champagne in hand, the day the Cincinnati Bengals picked him in the draft.

“He sent birthday cards. He came to my wedding. He just really cared for students,” he said. “And he became a mentor to me when I took this job last year.”

Joe Schmidt, who served as school president between Diebold and Santucci, said Diebold made being respectful a hallmark of his time at the school.

“He showed respect for everything he did. And the kids who wore a tie to school after he died, they may not know what they did was so respectful, but it was so respectful,” Schmidt said.

Diebold, a member of the Christian Brothers religious order, meant business but was compassionate and always had an open door, friends and colleagues said.

“You know the Empire Carpet man, with his calm, reassuring voice? I swear Brother Konrad sounded just like him and also had the stache and the bushy hair. Students loved him and felt comfortable talking to him,” said Abdon Pallasch, an alum and former Sun-Times reporter. “He was worldly and knowledgeable and well-read but could talk to kids who’d never left the Northwest Side.”

Diebold served as school president from 1987 to 2013. One of the first things he did as president was put in place a board of trustees that became integral in keeping the building and curriculum up to date and helped ensure students got admitted to good colleges.

Operating in the black while raising money for the many students who relied on financial assistance became his goal, and he was good at it, Schmidt said.

“And when the Christian Brothers started to lose their numbers, Diebold was very active in helping transition leadership at the school to lay people,” Schmidt said.

Diebold grew up in Minneapolis and attended Saint Mary’s University of Minnesota. He was the youngest of eight children, all of whom preceded him in death.

“He had a great life, to be able to be in a school that long, it just doesn’t happen that way anymore. He loved what he did. He preached the importance of touching hearts and created such a great atmosphere, a real strong family culture,” Schmidt said.

A visitation is scheduled for Sunday from 3 to 7 p.m. at Saint Patrick High School, 5900 W. Belmont Ave.

And funeral Mass is scheduled for Monday at 10 a.m. at St. Ferdinand Catholic Church, 5900 W. Barry Ave.