A former commissioner of the New York Police Department, Bernard “Bernie” Kerik, is dead at 69 years old. An Army veteran at the vanguard of the city’s 9/11 response, interior minister in Iraq, and convicted tax evader, his story reads like a ride on the Coney Island Cyclone — a rollercoaster of highs and lows.

The FBI director, Kash Patel, announced Kerik’s passing Thursday night on X, writing that his longtime friend was “a warrior, a patriot, and one of the most courageous public servants this country has ever known.”

Kerik, Mr. Patel noted, “was decorated more than 100 times for bravery, valor, and service, having rescued victims from burning buildings, survived assassination attempts, and brought some of the world’s most dangerous criminals to justice.”

The NYPD also eulogized its former chief. “For nearly two decades,” the department posted on X, “Kerik served and protected New Yorkers in the NYPD, including helping rebuild the city in the aftermath of 9/11. We offer our deepest condolences to his family and loved ones.”

The remarks were appropriate for the occasion, as were President Clinton’s at President Nixon’s funeral in 1994. “May the day of judging President Nixon on anything less than his entire life and career come to a close,” he said, alluding to Nixon’s resignation over the Watergate scandal.

People may extend the same compassion to Kerik. “He knew,” as Mr. Clinton said of Nixon, “great controversy amid defeat as well as victory. He made mistakes — and they, like his accomplishments, are part of his life and record.”

Kerik’s ride began with his birth at Newark, New Jersey. Only nine miles separate the city from New York on a map, but Kerik took a circuitous route to get there. He dropped out of high school, enlisted in the Army two years later, and served as a military policeman at South Korea.

While stationed at Fort Bragg, North Carolina, Kerik earned his GED. He joined the NYPD in 1986. He rose through the ranks to lead the Department of Correction, becoming the city’s top cop in 2000, just a year before 9/11.

The terrorist attacks presented policing challenges like none in American history, and Kerik’s performance earned him the nickname “America’s Cop.” In 2003, President George W. Bush entrusted him with commanding the provisional police force in Iraq.

Kerik’s rollercoaster car began to plummet not long after returning stateside. In 2004, Mr. Bush nominated him as the secretary of homeland security. Kerik withdrew from consideration over employing a nanny working illegally in America and pleaded guilty to that ethics violation in 2006.

Around the same time, Kerik was exposed as carrying on extramarital affairs. That he used an apartment at Battery Park City that had been donated for Ground Zero first-responders to rest cast a shadow over his stewardship of the 9/11 aftermath.

In 2009, Kerik pleaded guilty to eight felonies. Among them were making false statements to federal officials during vetting for the Cabinet position and tax fraud. He served almost three years of a four-year sentence before President Trump pardoned him in 2020.

When Mr. Trump granted that clemency, the White House issued a statement saying that Kerik had “focused on improving the lives of others” while incarcerated to become “a passionate advocate for criminal justice and prisoner re-entry reform.”

That might have been Kerik’s ticket for another ride to the top. Instead, after the 2020 election, he professed to have evidence that voter fraud by a supercomputer produced President Biden’s victory. He was later subpoenaed by the House to testify about the Capitol riots of January 6, 2021.

After what Mr. Patel called “a private battle with illness,” Kerik’s rollercoaster ride came to an end. It’s now up to historians to weigh his service against his scandals; the epitaph they settle upon may be along the lines of Nixon’s farewell to White House staff.

“Only if you have been in the deepest valley,” Nixon said, “can you ever know how magnificent it is to be on the highest mountain.” Kerik experienced both extremes — a life to be judged in its entirety by anyone seeking to make sense of his legacy.