A Minnesota man serving life in prison for a deadly 2004 flower shop robbery has gone before a judge reexamining his conviction and delivered a simple message: "I’m innocent 100 percent."

Marvin Haynes, 35, has spent nearly two decades behind bars for the shooting death of 55-year-old Randy Sherer, who was killed inside his family business in Minneapolis when Haynes was a teenager. Working with the Great North Innocence Project, the inmate successfully lobbied to plead his case before a Hennepin County district judge.

Judge William Koch held two days of hearings on the conviction and said Tuesday he would continue the case until Dec. 20, when the final witness is scheduled to testify.

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In initial police interviews with Haynes, detectives falsely asserted that they'd found fingerprints, DNA and surveillance footage linking him to the crime. He testified Tuesday that those claims were impossible, the Minneapolis Star Tribune reported.

Dressed in an orange jail jumpsuit, Haynes testified how he had slept until around 3 p.m. the day of Sherer's death. He was 16 at the time.

"I wasn’t there," Haynes said. "I’m innocent, 100 percent."

No physical evidence tied Haynes to the crime and he didn't match the physical description that witnesses provided to investigators. Several people who testified at his 2005 trial have since signed affidavits recanting their statements.

Haynes' lawyers argued that he was wrongfully convicted based on faulty eyewitness identification and improper police lineups. Innocence Project attorney Andrew Markquart told the judge that "the court will have ample basis to conclude that Mr. Haynes’ conviction is legally and factually defective and should therefore be vacated."

Former Hennepin County prosecutor Mike Furnstahl told the Star Tribune in March that he stood by the conviction and was "110 percent confident" that Haynes was guilty. He cited key testimony by several teenagers, including Haynes’ own cousin, who reported Haynes had made incriminating statements before and after the killing.

Assistant Hennepin County Attorney Anna Light reminded the court on Monday that a jury found Haynes guilty of first-degree murder in 2005 after a thorough examination of the evidence.

"That determination of guilt cannot be set aside lightly," she said.

Sherer and his sister were working at Jerry's Flower Shop on May 16, 2004, when a young man walked in saying he wanted flowers for his mother's birthday. Instead, he pulled out a revolver and demanded money and the security tapes.

Sherer emerged from the back, saying there was no money to take. His sister, Cynthia McDermid, fled as two shots rang out.

McDermid described the shooter to police as 19 to 22 years old with "close-cropped" hair. She looked at a photo lineup that didn't include Haynes and said she was 75% to 80% certain one man pictured was the shooter. But that man had an alibi.

Two days later, police received a tip pointing to Haynes. A booking photo showed him with a long afro and, at 5-foot-7, far shorter than the described shooter.

Investigators showed McDermid a photo lineup that included a photo of Haynes. But rather than the recent mugshot, they used a photo from two years earlier showing him with short, close-cropped hair. McDermid pinned him as the shooter.

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Detectives arranged an in-person lineup. McDermid and a middle schooler who claimed to have seen a man fleeing the flower shop each chose Haynes, with varying degrees of confidence.

Nancy Steblay, a retired professor emeritus of psychology at Augsburg University, said the police department's lineup method was flawed and created a high risk of error. She wrote in a report that mistaken eyewitness identification was faulted for nearly 80% of wrongful convictions in the first 200 cases overturned by DNA evidence.

During the 2005 trial, prosecutors relied on testimony from several minors who claimed to have heard Haynes bragging about the killing, including Haynes' cousin Isiah Harper, who was 14 at the time. Harper has since signed an affidavit recanting, saying officers threatened to send him to prison if he didn’t help corroborate their theories about the case.

"I was afraid," said Harper, now 34 and incarcerated for aiding and abetting second-degree murder in an unrelated case.