The headlines were everywhere: Charles Cullen, a nurse at Somerset Medical Center in New Jersey, had been charged with murdering one patient and attempting to kill another by administering lethal combinations of drugs. The so-called “Angel of Death,” who confessed to killing as many as 40 patients over the course of his 16-year nursing career, would eventually receive multiple consecutive life sentences.

At the time of Cullen’s employment at Somerset Medical, Miller was the hospital’s chief executive. Months before Cullen’s murderous activity was splashed across headlines in fall 2003, the hospital had conducted its own internal investigation following two unexplained medical incidents in the ICU (one patient survived, the other died).

While the three-month window between the internal investigation and Cullen’s arrest attracted scrutiny — a 2013 report on 60 Minutes claimed five patients were killed during that time — Miller maintains the hospital did not withhold any information and acted responsibly. “It’s easy to play Monday morning quarterback when you were not in the situation as it was unfolding,” he writes in his latest book, Moppin’ Floors to CEO. “I was proud of the role that the medical professionals played in his eventual capture.”

After Cullen’s arrest in December 2003, Miller did a series of high-profile interviews – with Katie Couric, Wolf Blitzer, and Morley Safer, among others – in an attempt to be forthcoming and set the record straight. Cullen had slipped through the hiring cracks at several hospitals in the region and Miller was determined to fix a system that had allowed it to happen.

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Despite his attempt at transparency, Miller sensed he wouldn’t survive the tragedy. After all, Cullen had worked for years, unchecked, under his leadership. “I took this personally. I’m hospital CEO,” he says. “People died here.”

In one way he was right. About seven months after Cullen’s arrest, the hospital asked for Miller’s resignation. It was a tortured time. After losing his job, Miller spoke to a headhunter who told him that thanks to his association with Cullen, “you’ll never get another job.”

Starting again.

Despite the tragedy’s unfathomable scale — investigators would uncover that Cullen killed 13 patients while employed at Somerset Medical — Miller refused to crumble under its weight.

Today, he coaches, consults, speaks and writes books on leadership and strategy in the nonprofit sector. He’s worked with Franklin Pierce University and Princeton University, but he now mostly consults organizations that focus on behavioral wellness, such as NewBridge Services, New Jersey Association for Mental Health and Addiction Agencies and Montgomery Academy.

When the hospital let him go, Miller’s professional future was one giant question mark. He tentatively began networking, searching for a new path that would provide his days with some much needed structure. Shortly after his dismissal, he had an informal meeting with Robin Albers, the regional vice president for the American Cancer Society in North Jersey. She asked for his advice on how to raise money, build a healthy board and develop a brand within the community.

Miller didn’t know what the next chapter of his life would look like, but these were questions he could answer. In his car after the meeting, a light bulb suddenly went off — maybe this was his calling. Since 2005, he estimates he’s coached “hundreds of nonprofit organizations,” helping them do everything from become more engaged with their communities, build better boards and raise more money.

In 2009, Miller did a review for Make-A-Wish New Jersey. Thanks to his advice, which included refining the nonprofit’s message, increasing the size of its board and identifying steps for succession planning, the organization is in a stronger position, says CEO Tom Weatherall. Another client, Xiomara Guevara, executive director of the Morris County Organization for Hispanic Affairs, cites Miller as a driving force behind a community center that helps residents navigate a path to citizenship. Without Dennis’s mentorship, she says, “we would not have moved forward with the project.”

“It was like a calling,” Miller says about his work with nonprofits. That’s not to say he wasn’t plagued by financial anxiety — life without a steady salary took some getting used to — but it felt good to regain his sense of purpose. As he puts it, “I’m a doer.”

Finding resilience in a difficult childhood.

To understand how Miller was able to build this new life for himself after Somerset, it’s important to know his exposure to mental illness didn’t start at Somerset Medical. As a boy, Miller was emotionally abused by his father, who he claims suffered from a “severe personality disorder.” Their relationship was so strained that at one point, in an effort to protect his mother, Miller says he tried to kill him with a butter knife. Intensely depressed, at age 20 he checked himself into a psychiatric hospital. It was a turning point in his life. He stopped taking drugs, went on to receive degrees from Rutgers and Columbia University’s School of Public Health, got married and had children. Therapy was a constant throughout.

Following Cullen’s arrest and his subsequent dismissal, however, these childhood demons resurfaced. “One of my challenges during this [post-Somerset Medical] phase of my life was finally addressing my real issue of self-worth and identity,” he writes in his book. “For too long my sense of ‘self’ was based on external factors such as title, income, recognition and what others thought of me.”

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Miller believes this painful soul searching ultimately turned him into a more compassionate and effective consultant and leader. His clients often tell him he has an ability to see their future before they do, a “unique skill set” he attributes to “the tragedy I’ve had in my life.”

The experience also made him acutely aware of the dangers of stigmatizing mental illness in the workplace, which not only injures employees’ well being but also hurts productivity and, by extension, a company’s bottom line. At Somerset, he recalls his own experience being embarrassed when sitting in a therapist’s waiting room. What if someone found out? He was a CEO, after all.

“The new thing I’m recommending people do is have a cultural change within the organization. Let’s stop stigmatizing it. Let’s have a discussion about it,” he says. “It’s OK to talk about it if you’re depressed. Let’s have an open discussion so people feel if they’re overburdened with family life problems that they can go to someone in the company.”

Miller has begun anew and he is bringing a depth to his work that he says is only possible after staring down chilling adversity.

He can’t undo the past. But he says he’s doing his best to create a better future.

Editor’s Note, May 10, 2016: A previous version of this story failed to include Miller’s comments on the hospital’s cooperation with authorities. Miller maintains that neither he nor the hospital withheld information from authorities. The headline was also changed to avoid any implication that Miller knowingly employed Charles Cullen.