With his people skills and Harvard degree, lawyer Jeffrey Walker could probably have sailed into a high-paying job at a prestigious firm, where wealth and influence often accrue with representing clients.

Instead, he spent a lot of his time in jail, interviewing people who needed a good defense.

“He just had this burning desire to fight for the underdog,” said fellow public defender Trenis Jackson. “Jeff Walker was one of the finest men I’ve ever known in my life.”

“He devoted his life to helping the poor and the indigent,” said his boss, Cook County Public Defender Amy P. Campanelli.

Mr. Walker died of biliary tract cancer Jan. 31, the same month he was diagnosed with the disease. He was 59.

For Mr. Walker, there was nothing like the feeling he got when he fought successfully for a client he believed had been wrongly accused.

Campanelli recalled how, after an acquittal, “He was ecstatic.”

Years ago, she and Mr. Walker had defended a man who’d been accused of an armed robbery that turned out to be a case of mistaken identity. He became enmeshed in the criminal justice system when he stepped outside on a work break to buy his nightly snack — a dill pickle.

“He was just coming across the street with his pickle” when the victim saw him, mistaking him for the man who robbed her, Campanelli said.

“I remember his [the defendant’s] mother always came to court,” she said. “I remember how wonderful we felt when we won.”

Lawyers who work in criminal courthouses sometimes get ground down by ugly crimes and heavy caseloads. But Mr. Walker, who did defense work for 34 years, was known for his enthusiasm and dogged investigations.

“Jeff tirelessly visited clients and witnesses in prisons throughout Illinois,” said Harold Winston, a supervisor in the Legal Resources Division of the public defender’s office.

“He was just always digging to find a way to assist a client,” Jackson said.

Mr. Walker was “a fearless warrior for his clients, and he called out racism when he saw it,” said Karen L. Daniel, director of Northwestern University’s Center on Wrongful Convictions.

Campanelli said: “I admired him greatly for his courage and integrity. We went out on the streets and investigated cases. When he was up there cross-examining someone, he would never stop without coming to the table and asking [his co-counsel], ‘Is there anything else? Is there anything I missed?’ ”

Whether on the road for a jail visit or working from an office crowded with court files, he never lost his hearty laugh, colleagues said, and always made time to welcome new lawyers to the public defender’s office.

He grew up the oldest of four children in Roseland. His father Walter, a teacher, was active with the Chicago Teachers Union. His mother Bette was a nurse. Decades ago, one of his relatives was exonerated and released after a wrongful murder conviction in New Jersey, which might have inspired his public defense work, according to his wife, Learetta Tyson Walker.

While attending St. Ignatius College Prep from 1970 to 1974, young Jeffrey was a two-time champion of a statewide Latin competition, according to high school friend Ron Garner.

“Jeff was always a gentle soul and a friend to everyone,’’ said another St. Ignatius classmate, William R. Kunkel, now general counsel for the Archdiocese of Chicago.

Mr. Walker earned a bachelor’s degree from Harvard University and a law degree from Boston University.

He started his career in the Office of the State Appellate Defender. Joining the Cook County public defender’s office in 1988, he worked in the felony trial division. His last assignment was in the legal resources division, working on appeals.

In 1987, he met his future wife at a Cook County Bar Association gathering at the DuSable Museum. They got married in 1989 at St. John de la Salle Church at 102nd and King Drive. They had a son, Alexander, and Mr. Walker coached his AYSO soccer teams from preschool until eighth grade, according to his wife, who said, “He was always there for his son.”

Mr. Walker loved straight-ahead jazz. He listened to legends including John Coltrane, Miles Davis and Charlie Parker and was thrilled when he got to attend a party for Ornette Coleman after the saxophone legend performed in Chicago.

Mr. Walker liked to cook and eat barbecue. He loved to read, especially on jazz, history and politics. He served on the executive board of the Chicago Coalition for Police Accountability and was active with the Chicago Justice Project, Winston said.

In addition to his wife, son and mother, he is survived by his sister Carolyn and brothers Michael and David. Services have been held.