Former Hennepin County Attorney Tom Johnson, a pioneering criminal justice advocate and most recently ombudsman for victims of Catholic clergy abuse, lost his six-year battle Monday with advanced prostate cancer.

Johnson, 75, died at his Minneapolis home surrounded by his wife, Victoria, and his four adult children. Though he hadn't held public office since stepping down as county attorney after 12 years in 1991, he had remained a public force for justice reforms through both public advocacy and personal relationships, serving as a mentor to many state leaders.

"His influence went way beyond any office that he held," said David Lebedoff, who met Johnson in 1972 when both were young lawyers working on the presidential campaign of U.S. Sen. George McGovern.

It's significant that Johnson died amid the recent upheaval in Minneapolis, Lebedoff said, referring to the unrest in the wake of the killing of George Floyd by a police officer. Johnson "was with us at a time when no one else was pointing out disparities in our justice system," he said.

Last Christmas, Johnson wrote his own obituary. His tone was lighthearted, but he also wrote that none of his jobs gave him more satisfaction than "calling attention to the unacceptable racial disparities in the justice system and their cost to society."

In an interview with a Star Tribune editorial writer in 2015, Johnson lamented his shortcomings in meeting the challenges faced by black Americans. "On a number of occasions I thought about plunging in and figuring out what could be done to change a particular situation," he said. "Too often, I didn't, at least not with the vigor I typically try to bring to resolving an issue."

But his accomplishments were substantial. In 1989 he founded CornerHouse, a nationally recognized advocacy center for children who are victims of sex abuse. He founded and sat on the board of the Minnesota Justice Research Center, which seeks fair and humane treatment for those in the criminal justice system. Last week he participated in his last board meeting online.

Johnson led the now-shuttered nonprofit Council on Crime and Justice (CCJ) from 1998 to 2007 and directed groundbreaking research on racial disparities in the criminal justice system. He also practiced environmental law at Gray Plant Mooty in Minneapolis, where he fought the Southwest light-rail line.

Johnson grew up on a farm in Brookston, Minn., and graduated from Duluth Central High School. He earned degrees in physics and law from the University of Minnesota and a master of laws degree from the London School of Economics.

At age 28, he was elected to the Minneapolis City Council. In his self-written obituary, he said he walked around City Hall thinking, "If the public only knew how little I know."

But Johnson learned quickly. He fought for truth-in-housing inspections and campaign finance disclosures, and prohibition of discrimination based on sexual orientation. He also got passed a ban on plastic milk cartons, though the ban lasted only a few months.

Within hours of his death, Gov. Tim Walz, U.S. Sen. Amy Klobuchar and Archbishop Bernard Hebda posted tributes to Johnson on social media. Walz called Johnson "a voice for the voiceless, a passionate pursuer of justice, a loving husband, and a wise and good-humored father," and Klobuchar, herself a former Hennepin County attorney, said Johnson "always did good."

Hebda wrote that Johnson's "compassionate work on behalf of victims of clergy sexual abuse was inspiring. We are a better church and a better community because of Tom."

Hennepin County Attorney Mike Freeman said he met Johnson in 1978 and remained a lifelong friend. Freeman said Johnson recruited him to run for county attorney in 1990 and that the two met regularly. The last time was six weeks ago, when Johnson gave Freeman a written agenda for reform.

"Tom never stopped thinking and being an activist," Freeman said.

Mark Haase, ombudsman for the state Department of Corrections, also considered Johnson a mentor. Haase, who ran unsuccessfully against Freeman in 2018, first met Johnson when he was a law student and intern at CCJ in 2005. "He treated me like I knew exactly what I was doing, like an equal," Haase said.

The Rev. Daniel Griffith, pastor at Our Lady of Lourdes Catholic Church in Minneapolis, met Johnson through Victoria, a parish administrator. "In 18 years in the priesthood, I'm not sure I met someone who was a better human being," Griffith said. "His sense of justice was off the charts."

Two days after Johnson's final birthday in April, his son Hunter took him for a Ferris Bueller-style tour of the Twin Cities in a borrowed green 1974 Triumph Spitfire convertible.

"Everywhere we drove in the Twin Cities, my dad had a significant memory or story to share with me about his life; his first campaign headquarters, his old running route, a favorite cafe," said Hunter, of Minneapolis.

Besides his wife and son Hunter, Johnson is survived by his daughters, Jill Steigauf of St. Paul, and Kayla Johnson Castañeda of St. Paul, communications director for Walz; son Ben, of New Haven, Conn.; brothers, Jerry and Warren; and sister, Susan Henderson.

Hebda will lead a livestreamed service for Johnson at 10 a.m. Saturday at Our Lady of Lourdes. Due to COVID-19, only family and some close friends will attend.