He considered slipping quietly away from his office — packing and leaving in the dead of night, he jokes, like the Baltimore Colts football team once famously did.

But his superintendent would have none of that. And so last August, Frank DeAngelis publicly announced his impending retirement as principal at Columbine High School.

The move came with side effects. Stomach pain, chest pain — serious enough that he saw his doctor. A battery of tests raised no concerns but one question: When had DeAngelis last talked to his counselor?

It had been awhile, so he went in for an emotional tuneup.

“It was stress,” recalls DeAngelis, 59. “He said, ‘Frank, your head is telling you that, come June 20, you’ll no longer be principal. Your head knows that. You’ve come to realize that. But your gut — your heart and soul — hasn’t caught up with what your head is telling you.’ “

He will have spent 18 years leading Columbine, 15 of them since the April 20, 1999, school shooting that claimed the lives of 12 students and a teacher, injured dozens more and emotionally devastated a community.

Some studies put the average stay for a high school principal around four years.

Since the tragedy, he has remained a highly visible presence in the discussion of school safety, which changed drastically as lessons of the law enforcement response that day were transformed into policy.

PHOTOS: Columbine High School principal about to retire

The forces that kept DeAngelis at Columbine, where he started as a 24-year-old social studies teacher and coach, have largely been tied to personal and professional factors ranging from survivor’s guilt to a sense of spiritual imperative in his response to the tragedy.

DeAngelis’ promise to see his students through the turmoil expanded over the years, until he determined that he would remain principal — with the support of district administration — until even toddlers who had been in feeder preschools at the time of the shootings had graduated.

DeAngelis remains almost synonymous with the school — in large part for his efforts to rebuild Columbine, but also for his willingness, bordering on a sense of obligation, to become a public voice and resource addressing other school tragedies.

He has, at once, sought to strip Columbine of the school-shooting stigma and embrace it as an undeniable touchstone of a career reflected in the lives of many people it has touched.

Diane Meyer remembers that, for reasons logical only to a high school sophomore in the early 1970s, she felt compelled to pick between two prospective boyfriends.

One had a bit of a bad-boy rep. But the other guy — Frank DeAngelis, a year ahead of her at Ranum High — came from a big Catholic family like hers and seemed like a really nice guy.

They dated for two years in a pre-digital romance marked by a trail of handwritten love letters. The coupling held more urgency for Frank, who wanted to get married right out of high school. Diane had other plans.

They went their separate ways, fell out of touch. Diane married, had children and divorced. But she always kept the love letters. Frank married and launched his career as a teacher and coach.

As Diane settled into single life, she half-joked that she might eventually consider marriage again — if she ever met anyone half as nice as Frank.

DeAngelis had another love affair — with baseball. Terry Conley, the Columbine High School principal, noticed him first as a coach. The details have faded in his memory, but it probably was when DeAngelis served as an assistant at Wheat Ridge High School.

Something about the young man stuck with Conley.

“How about ‘aura’?” he says now. “I saw him with his team and the way he handled them, the care that he demonstrated. That’s why, in my opinion, they were such a good team. If he talked to them, he left them confident.”

Soon after, when a position for a social studies teacher opened up — and, coincidentally, a baseball coaching slot — the 24-year-old DeAngelis landed in Conley’s office.

“I hate to admit it, but I was pretty intuitive in terms of my hiring,” says Conley, the second principal in Columbine’s succession. “If I had 10 questions and on the third question a person sent me the message of how much they cared for kids, for teaching, for coaching — if they were empathetic and energetic and bright — I got excited.”

Conley, now retired, had just such an experience with the young teacher, who left his office with a new job. DeAngelis would leave the school only once, to teach at Deer Creek Middle School for a year.

“I was probably a little brash in hiring people on the spot,” Conley says. “But when I reflect back on the whole thing, I’d say Frank was the best hire I ever made.”

Almost as a footnote, DeAngelis’ Rebel teams won two state baseball championships, in 1987 and 1991.

Erin Hernandez was a freshman, heading down a hallway with a bunch of other girls on their way outside to run for gym class. And then, around the corner came the principal moving quickly toward them yelling, “Get in the gym! Get in the gym!”

“At first, I was just confused,” recalls Hernandez. “It felt surreal. We all thought it was a joke. It was when we heard the gunshots that fear sweeps through you.”

Some people in the group of students behind Hernandez actually saw the shooter, who appeared at that moment to be heading in their direction.

Seconds earlier, DeAngelis had come face to face with one of the gunmen, who fired a shotgun blast that shattered glass behind him. DeAngelis had heard the voices of Hernandez and other students and immediately sought to move them away from danger.

He herded the group to a locked storage room off the gym. Hernandez — her last name was Flynn back then — watched him fumble with his massive key chain and somehow find the right key to open the closet.

“I remember he told us stay in here, don’t leave,” she says. “He said, ‘I’m going to give you a password.’ The way I remember, it was ‘Oranges in the newspaper.’ I don’t even know honestly if that’s right anymore.”

Minutes later, he returned and guided them out of the school.

But for Hernandez, who’s now a teacher at Falcon Creek Middle School, that chance encounter with DeAngelis formed the basis for a lifelong relationship.

“I think initially, it was just a process of grieving together, finding ways to cope with what we witnessed, what we heard,” she says. “Then I realized this man saved my life.”

He became family. He attended her wedding. The almost daily notes she would write to him in the immediate aftermath of the shootings gradually receded to periodic e-mails.

Still, every year, she reaches out to him around April 20.

“I wouldn’t be who I am and what I am if it weren’t for him,” she says. “Every time we get together, that’s what we talk about, even all this time later.”

Tom Tonelli sat in the church with hundreds of others from the Columbine community days after the attack, struggling to understand what had happened to them. The details of the tragedy had been slow to emerge, but its impact overwhelmed them and brought them together in a prayer vigil at St. Frances Cabrini Catholic Parish.

Tonelli, a social studies teacher, saw his principal sitting in the congregation, as distraught as anyone. Monsignor Kenneth Leone, the pastor known as Father Ken who eventually would become a close spiritual adviser to DeAngelis, stood in the sanctuary and called for him to come forward.

“After everything happened, he felt so much blame, so much guilt,” Tonelli says. “We all did. What could we have done? How could this have been different? What was our role in this whole thing?”

As DeAngelis approached, there was clapping, a surge of support. Tonelli remembers DeAngelis, shoulders slumped from the weight of events, stepping to the front of the church. Then Leone asked others to come forward and lay their hands on him.

“Frank is in the middle, he’s standing, but he can’t look up,” Tonelli says. “He is devastated. He is broken. Probably 30 people put their hands on him, everyone else is extending hands toward Frank. Then Father Leone prays for Frank.”

Tonelli, who sat in DeAngelis’ social studies class as a 14-year-old kid, played football for him and later followed him into teaching, felt that the beleaguered principal reached a crossroads at St. Frances Cabrini.

“I think that event was a pivotal point in the weeks and months and years ahead that he could go back to,” Tonelli says, “that in spite of everything, God loves him and God’s going to use him.”

Bill Bond heard echoes of his own tragedy in the Columbine attack. In December 1997, a 14-year-old boy had pulled a handgun from his backpack and fired into a youth prayer group, killing three and injuring five more before classes began at Heath High School in West Paducah, Ky.

Less than two years later, Bond — at that point still the principal at Heath — picked up the phone and reached out to a man he’d never met in a gesture that has become far too familiar now, after 15 times and counting.

He found DeAngelis “in kind of a fog” after the Columbine attack but already trying to look forward. School shootings hadn’t quite become recurring touchstones in American culture when the West Paducah incident unfolded.

Over time, he noticed a metamorphosis: DeAngelis renewed efforts to make all students feel welcome, even in such a sprawling school where individual needs can get lost.

“There wasn’t a template for rebuilding a school and holding a community together,” Bond says. “Frank built that template.”

Bond now serves as a school-safety specialist for the National Association of Secondary School Principals. He and DeAngelis plan to collaborate professionally in the months ahead, while DeAngelis also consults for Jefferson County Public Schools on emergency-management matters.

Their experience with school shootings mirror those of a growing number of principals. But some details remain unspoken.

“It’s a club Frank and I know we belong to, and no one else wants to join,” he says. “You don’t talk about the rules of the club. You talk about how the club can help.”

When the Columbine attack happened, Diane Meyer sent Frank a card on behalf of her whole family, a brief thoughts-and-prayers message that wound up, unopened, in a box in his basement with a few thousand others. He had begun a regimen of reading 25 a day, but stopped when the sentiments — most encouraging, but some spiteful and threatening — became an obstacle to his own healing.

It would be three years before he tried again. His spirits battered and his 18-year marriage at an end, he opened some envelopes. One of the first was Diane’s. After 30 years, he still remembered her parents’ phone number and tracked her down. She heard his voice for the first time in decades.

“He was not in a good place,” Diane recalls.

She was 16 years past her divorce but struggling to deal with her father’s failing health. It was February 2002, and she and Frank offered each other support over the course of many phone conversations. They didn’t reconnect in person until her father’s funeral that April.

And by then, as another anniversary of the Columbine shootings approached, things had grown tense.

“By the end of March, the beginning of April, I couldn’t relate to him,” Diane says. “He kept the conversations short. I felt like I wanted to reach out, but I didn’t know if that’s what he wanted. I almost threw in the towel. I didn’t know where he was coming from.”

The erratic Aprils were a recurring theme, a symptom of his own difficulties handling the memory of a most horrific day. Under stress, he pulled away.

But Diane stuck with him.

They’ve been engaged for more than a decade — an extended second courtship, although both insist marriage awaits in the near future. They’re building a house together, something Diane hopes will provide enough of a diversion to ease Frank’s withdrawal from the daily life of Columbine High School.

“My family thinks he saved me,” Diane says, “and his family thinks I saved him. We came back together, and it works.”

Brad and Misty Bernall never really expected to stay in touch with Frank DeAngelis after they lost their daughter, Cassie, at Columbine.

But every April, they receive a letter from him — as other victim families do — inviting them to visit Columbine on April 20, when the school isn’t in session. They see him at the annual Run for Remembrance.

And every year, they get a call on Nov. 6 — Cassie’s birthday.

“I never expected that kind of compassion,” Brad says. “We didn’t know Frank, what kind of man he was. It was wonderful to find out we had this principal who truly was concerned about everyone affected.”

They heard the criticism of DeAngelis after the shootings and wondered: Should someone have known? Should something have been done? But they never felt the claims of bullying and jock culture rang true. And ultimately, they never figured DeAngelis bore responsibility for what two killers did.

Although the Bernalls sued along with other victim families, they say they did so targeting the Jefferson County Sheriff’s Office with an eye toward changing the way first-responders approach active-shooter incidents. Authorities remained on the perimeter while the shooters ravaged the school — a protocol that since has been reversed.

“In our eyes, we were not suing Frank by any means,” Misty says, noting the family did not press any further legal action. “I just know that we were all very different families, we all grieved very differently. In my mind, you just let people do what they need to do.

“I’m sure Frank sees that, too.”

Paula Reed doesn’t remember whether Frank DeAngelis volunteered to play the part or if someone asked him.

But once he had donned a graduation robe, slipped into character as 18th-century theologian Jonathan Edwards and delivered the classic fire-and-brimstone sermon “Sinners in the Hands of an Angry God” to critical acclaim, teachers lined up to book him for their classes.

He has performed for all of Columbine’s 10th-grade English teachers during their unit examining literature of the Puritan period. Reed, who has known DeAngelis for nearly 28 years, introduces him as a guest speaker.

“The kids kind of giggle at first, and he starts off really soft-spoken,” Reed says. “But then, five lines in, he talks about how there’s no reason that God is not at this very moment casting them into hell. And when he says ‘hell,’ he slams his hand on the podium, and the kids jump.

“He kind of ad-libs, and he’ll throw a kid’s name in: ‘So-and-so, I know that you were misbehaving last weekend, and God is not pleased.’ And he loves it, absolutely loves it. He’ll bend over backwards to make it fit into his schedule.”

Reed notes that DeAngelis has done this every year, never failing to shoehorn it into his administrative schedule.

“Ever since he left the classroom,” she says, “it’s like he’s been fighting to get back into it.”

Andy Fetchik says that one of the first things he heard from the man on the other end of the phone line was this: “You’re not going to remember anything we talk about today, but please take down my number and call me if you ever need anything.”

It was early March 2012. Fetchik, the high school principal in Chardon, Ohio, a small town northeast of Cleveland, still reeled from a shooting in which a 17-year-old boy walked into the school’s cafeteria and opened fire, killing three students and wounding three others.

Frank DeAngelis — paying forward what the Kentucky principal, Bill Bond, had once done for him — continued his practice of reaching out to administrators in schools shattered by violence. Fetchik soon came to lean on the Columbine principal, as others have.

“True to his word, I didn’t remember much of the phone call as we picked up the pieces,” Fetchik says. “But I did take down his number, reached out to him several times in the months following that for advice. And he provided guidance. That advice was priceless for us.”

In February, on the second remembrance of the shootings, DeAngelis visited Chardon and spoke to a meeting of more than 100 middle and high school staff before addressing the larger community that evening.

One-on-one in Fetchik’s office, he shared the cautionary tale of his failed marriage, the role of his faith, how to look beyond the demands of being a leader of the school community.

All of this moved Fetchik to realize that he must also reach out — difficult as that may be.

“I’ve had the opportunity to offer the same advice Frank gave me,” he says. “When you hang up the phone, there’s almost a sense of healing. It’s cathartic.”

Sometime after school is out, late at night when the building sits quiet and dark, Frank DeAngelis will return to his office at Columbine and begin removing the memorabilia that covers the walls.

It hasn’t struck him yet, the full breadth and depth of his career. And so the dismantling of the hundreds of photos, certificates and other artifacts is a task best left for a time when he can privately reflect.

He knows it will be difficult and emotional because a part of him does not want to go. Part of him will never want to leave.

“I’ve been around people who are counting the days that they have until they retire, how many faculty meetings they have left, how many Mondays they have left,” DeAngelis says. “I’ve never been there. The thing I’m most proud of, as I’m ready to walk out the door, is that I love what I’m doing. This is really difficult, and I am counting the days. But to me, each day that goes by is one less day I get to spend at Columbine High School.

“It’s bittersweet.”

For DeAngelis, all-school assemblies have always held a special place in his heart. He gradually overcame his initial stage fright at addressing 1,700 kids until, over the last several years, he fully embraced his inner ham.

He rode into the school gym on a motorcycle one year, then pushed the limits of his showmanship by singing Sinatra and Manilow, strutting in dressed as Willy Wonka, fake-wrestling the school’s top heavyweight.

He needed something spectacular for his last act.

“In my mind, I said I’ve got to figure out a way to fly,” he says.

The planning began months ago, after DeAngelis — who has an admitted fear of heights — consulted the drama department on how it simulated flight in the student production of “Peter Pan.”

He hooked up with a company that has the necessary lift and harnesses and did a practice run before the real deal on a Friday in late April.

In a darkened gym, DeAngelis, in full formal attire, launched himself from the lift and swung back and forth over the assembly to Sinatra’s rendition of “My Way.”

When he came back to earth, he tied the stunt to his story about establishing goals, facing fears and believing in yourself — lessons he always hoped students would take with them when they left Columbine High School.

For DeAngelis, facing fears meant staying. Now, 15 years after the nightmare of April 1999, he regards this not as evidence of personal courage or perseverance so much as a celebration of the spirit that endured among the students and staff who carried him.

“I needed this school,” he says, “more than it needed me.”

Kevin Simpson: 303-954-1739, denverpost.com or twitter.com/ksimpsondp