John Ferak

USA TODAY NETWORK-Wisconsin

In the early 1990s, after a decade of practicing law, Kathleen Zellner didn't have a successful wrongful conviction case attached to her name. The Northern Illinois University law school graduate was working in the booming suburbs west of Chicago, and business law, not criminal justice, was her main focus of litigation.

Zellner was unfamiliar at the time with Steven Avery, the short, bearded man from Manitowoc County who was serving a long prison sentence after being convicted — wrongfully, it would turn out — of the attempted murder and rape of a local businesswoman near Lake Michigan.

The 1988 downstate Illinois murder case that would eventually transform Zellner's law practice wasn't on her radar yet, either. That case wouldn't come into view for her until December 1992. By then, Zellner was branching out her legal expertise, taking on post-conviction appeals. An agency in Illinois that helps pair indigent convicts with appellate lawyers recommended Zellner examine the case of Joe Burrows, a convicted death row inmate. She accepted the case.

"I'm not expecting you to rely on me saying I'm innocent," Burrows wrote to Zellner, the Los Angeles Times reported. "Examine my case, examine the record. Make up your own mind."

She did, and 24 years later Zellner stands as the country's best-known litigant for the wrongly convicted. This year, she staked her professional reputation on proving that Avery — the subject of the "Making a Murderer" docu-series on Netflix — was the victim of a second wrongful conviction in Manitowoc County. Avery is serving a life sentence with no chance for parole after a Manitowoc County jury convicted him of killing photographer Teresa Halbach on Halloween 2005.

Zellner's first-ever wrongful conviction case — freeing Burrows from death row — offers a window into the techniques she's apt to undertake in trying to prove Avery's innocence. It's also a good comparison to show how slow the justice system operates, even in proven wrongful conviction cases.

"There are similarities between the Burrows and Avery cases," Zellner wrote USA TODAY NETWORK-Wisconsin. "Both men were targeted by law enforcement from a young age. Both cases involve a coerced confession and both cases have an alleged crime scene that does not make sense."

Zellner is in her ninth full month representing Avery. It took Zellner more than twice that long — 21 months — to prove Burrows' innocence. Last May, Zellner alerted thousands of her Twitter followers that she intended to have Avery exonerated by next Mother's Day. That remains to be seen.

Meanwhile, Zellner has vowed to uncover scientific evidence that reveals someone other than Avery and his co-defendant, nephew Brendan Dassey, was the killer. Her detractors find her claims ridiculous. But Zellner has been down this road before — it's how she convinced Burrows' original sentencing judge of his innocence in 1994.

"The chief difference is that Burrows was a more difficult case to unravel than I believe Avery's will be, thanks in large measure to advances in forensic science," Zellner wrote USA TODAY NETWORK-Wisconsin.

Here are the key events involving Zellner's first major wrongful conviction case:

When: Nov. 6, 1988.

Where: Sheldon, Ill., population 1,000, located about 60 miles south of Chicago.

Victim: Bill Dulin, 88-year-old retired farmer known as "the apple man." Dulin operated a fruit stand in sparsely populated Iroquois County, a farm region near the Indiana border.

Crime scene: On Nov. 8, 1988, Dulin's body was discovered on his living room floor. He was killed in his long underwear and there was ceiling plaster on the floor, evidence of a gun struggle. A few shots had deflected off his ceiling. The fatal wound lodged in his neck. Blood was found elsewhere, including on a desk and various papers. Those stains were not Dulin's blood.

Bank incident: The day Dulin's body was found, a young man and woman were questioned by authorities after they tried to cash a $4,050 check with the murder victim's forged signature. The woman, Gayle Potter, confessed being in Dulin's house when he was slain, but she implicated two other men as the killers. She claimed Joseph Burrows pistol-whipped her, causing her to bleed, as she valiantly tried to stop Burrows from killing the retired farmer. The Iroquois County Sheriff rushed out to arrest Burrows and Ralph Frye, who lived 60 miles away, without investigating their whereabouts on the night of the murder.

Dubious prosecution: Prosecutor Tony Brasel applied enormous pressure on Frye and Potter to finger Burrows as the killer. Frye and Potter were placed in jail cells next to each other, allowing them to talk. Frye was learning-disabled and had an IQ of 75. Although Frye later wrote the judge insisting he was innocent, he confessed during an intense interrogation shortly after his arrest. He later said the Iroquois investigators coached him what to say during that interrogation. Brasel visited the jail numerous times before Burrows' capital murder trial to coach Potter and Frye, Potter would say later. "Tony Brasel would supply me with the fact and then I had to supply the supporting story for it," Potter told the Los Angeles Times.

Hung jury, conviction: Burrows' innocence boiled down to the credibility of co-defendants Potter and Frye. No physical evidence from the crime scene implicated Burrows. At his first trial, Burrows' lawyer called a handful of people who insisted Burrows was watching television in their living room, in Urbana, which was 60 miles away. The jury was deadlocked. It could not reach a unanimous verdict. At the second trial, Burrows' lawyer inexplicably chose not to call Burrows' alibi witnesses to testify. It took the jury only three hours to find Burrows guilty. "So many people know that I'm innocent, but yet here I am about to be sentenced. ... I don't want to be sentenced to death, but I can't help wondering (if it is) preferable to living in a world where such corruption and injustice goes unchecked," Burrows declared at his sentencing. Judge John F. Michela ordered Burrows to die by lethal injection. In March of 1992, the Illinois Supreme Court rejected Burrows' appeal in a unanimous verdict. Around that period, Frye, the other convicted co-defendant, recanted his confession and his trial testimony against Burrows as part of an investigative newspaper story in the Champaign, Ill., newspaper. Doubts about the veracity of Burrows' murder conviction were starting to emerge.

Zellner takes case: Burrows had already been incarcerated for four years when Zellner took the death row inmate's case. Much of her effort explored suspicions of prosecutorial misconduct and her belief that Iroquois County did a careless and sloppy murder investigation. Zellner became sure of Burrows' innocence, but unsure of the real killer's identity. She started traveling to the women's prison in Dwight, Ill. She met with Potter, the manipulative co-defendant who implicated her client and Frye. During their interviews, Potter boasted of being a big-time cocaine supplier who supposedly had partied with international drug lords and famous politicians. Zellner gleaned that Potter was a delusional sociopath, though personable. During many of their prison visits, Zellner steered their conversation to the plight of Burrows' family. His death sentence left him permanently separated from his wife and three children.

Evidence discovered: Zellner's associates made a key discovery. The special prosecutor had withheld key information from Burrows' trial lawyer that could raise doubts about Burrows' guilt, had the information come out at trial. The prosecutor had failed to turn over a letter Potter wrote from jail shortly after her arrest. She implored a male friend to notify sheriff's deputies that he saw a blue truck parked outside the victim's farm. (Potter claimed Burrows used a blue truck as their getaway vehicle though no such truck existed.) "Police are going to say I was the one who killed Mr. Dulin ... Tom, PLEASE, I'm begging you," Potter wrote.

Witnesses surface: Several people who knew key facts regarding Dulin's murder were not compelled to testify at Burrows' trial. One was Jana West, who could have confirmed Burrows' alibi. Even more importantly, the day after the murder, Potter confessed to West that she killed the farmer during a struggle over the gun. Potter went to Dulin's farmhouse to borrow money, which she had done before. Also, Potter's ex-boyfriend saw Potter within hours of the crime. She was sprayed with blood and confessed to doing the killing. Even though Zellner was making giant strides by early 1994, her client was losing hope as he remained on death row. Burrows wrote in his journal, "I will write the court and waive all my rights and petition the court to proceed with my execution as soon as possible," the Los Angeles Times reported.

Potter confesses: Zellner made at least two dozen visits to the women's prison in Dwight to confer with Potter. Then, in April 1994, Zellner unveiled her own theory about Dulin's murder. The victim, Zellner explained, was small and frail, barely 5-feet-tall. In contrast, Burrows was big and burly. The scene showed obvious signs of a struggle. Gunpowder soot was on the victim's long john sleeves. Bullets were fired into the ceiling. Potter, like the victim, was short. "The killer was about the same height and strength as Dulin," Zellner revealed. She theorized a woman was the killer.

"A woman did do it," Potter told Zellner. "I was there alone. I shot Bill Dulin."

Burrows freed: In September 1994, Zellner implored John F. Michela, the same judge who sentenced her client to die of lethal injection back in 1989, to set him free. "Joseph Burrows has spent 1,865 days on Death Row in a 5-by-7 cell for a crime he did not commit. It is time for Mr. Burrows to go home. We should not waste another minute of Mr. Burrows' life," Zellner argued. The judge agreed, rejecting a last-minute desperate plea from an Illinois appellate prosecutor. That day, Burrows emerged from the courthouse sporting a tattoo across his arm proclaiming, "Die Free!" In the end, Potter, who could not be resentenced, received an additional five-year term for committing perjury. Frye, the other wrongfully convicted defendant, was exonerated in 1996.

After being freed for a murder he did not commit, Burrows struggled to regain his footing in life. He eventually went back to prison in Illinois, convicted of methamphetamine manufacturing. He spent three years in prison for that crime. In 2009, a year after finishing that sentence, Burrows died at 56. "I thought he had a tragic life," Zellner told The News-Gazette. "Being wrongly convicted made him understandably bitter. ... As a person, Joe was a good man. He loved his children and wife, but he was under so much pressure."

Sources: "The Framing of Joseph Burrows," published Dec. 18, 1994, Los Angeles Times; "Death Row Battle Ends With Freedom," Sept. 9, 1994, Chicago Tribune; court records, "Exonerated Man, Joe Burrows, Finally at Peace," Oct. 23, 2009, The News-Gazette; National Registry of Exonerations.

John Ferak of USA TODAY NETWORK-Wisconsin: 920-993-7115 or jferak@gannett.com; on Twitter @johnferak