The slaying in the small town of Poland in central Louisiana in 1996 was horrific— a man, his sister, his sister's daughter and her infant son — all shot to death in their home. Law enforcement officers quickly zeroed in on Darrell Robinson as a suspect. Five years later he was sentenced to death for the killings.

Last week, with the help of three Minneapolis attorneys and a paralegal, the Louisiana State Supreme Court reversed the conviction, vacated Robinson's death sentence and remanded the case to the district court for a new trial.

"The defendant did not receive a fair trial, or a verdict worthy of confidence," wrote Louisiana Supreme Court Chief Justice John Weimer.

The high court said the case against Robinson was circumstantial and cited significant evidence that prosecutors failed to turn over to the defense that could have persuaded a jury that Robinson was innocent. It also said a key witness, a jail house snitch who claimed Robinson confessed to him, had cut a secret deal with prosecutors which undermined his credibility.

Robinson, 55, had been on death row at the Angola State Penitentiary for 23 years, most of it in solitary confinement.

It is believed to be the first time the Louisiana Supreme Court has reversed the conviction of a death row inmate on the grounds that prosecutors withheld evidence, said attorney Matilde Carbia, who worked on the case. She is with the Mwalimu Center for Justice in New Orleans which represents inmates sentenced to death in Louisiana.

"We would not have been able to so fiercely advocate on behalf of Robinson without the incredible work of our co-counsel" in Minneapolis, Carbia said.

The pro bono Minneapolis legal team included attorneys Edward Cassidy and Lousene Hoppe of Fredrikson & Byron law firm, Kevin Riach, who has a solo law practice, but began working on the case when he was at Fredrikson, and paralegal Leslie Anderson at Fredrikson. They logged thousands of hours on the appeal.

"This is a case of true innocence," said Riach. "He didn't commit these murders."

Four justices voted to overturn the verdict and sentence. In a dissent, one justice supported Robinson's conviction but favored a new trial on the sentencing phase while two justices supported both the conviction and death sentence. "Defendant had a fair trial," wrote Justice William J. Crain.

Attorney Hugo Holland Jr., brought in by prosecutors to defend the conviction, made clear he disagreed with the Supreme Court decision and sided with the justices in the minority.

"Minority is right," he said in an email. "Majority is wrong. Yes we are retrying this murdering piece of crap."

A statement issued by Rapides Parish District Attorney Phillip Terrell's office, and published in the Town Talk, a newspaper in Alexandria, La., said, "All those who worked in the DA's office at the time of the trial have long since retired. The current administration adamantly disagrees with the decision of the high court."

According to court documents, Robinson met Billy Lambert while they were in treatment for alcoholism. Lambert invited Robinson to live with him in exchange for performing chores on his farm. He moved into Lambert's spare bedroom, but Robinson began drinking again and Lambert told a cousin he intended to kick Robinson out of the house.

Prosecutors argued that sometime in the morning of May 28, 1996, Robinson, who was drunk, entered the house, shot to death Lambert, his sister Carol Hooper, Hooper's daughter Maureen Kelly, and Kelly's infant son, Nicholas Kelly. Then Robinson took Lambert's Ford truck and swerved into traffic, knocking a mirror off the vehicle about 11 miles away and was eventually arrested after he parked his car and ran into the woods.

He was unarmed. A small blood spot was found on the bottom of his left shoe, consistent with Kelly's DNA.

While awaiting trial, Robinson shared a cell with Leroy Goodspeed who claimed Robinson confessed to the murders then threw the gun off a bridge. A convicted felon, Goodspeed faced a life sentence for new crimes he committed, but at trial he and prosecutors told the jury he had no reason to lie and had cut no deal. Robinson was convicted on four counts of first-degree murder.

The Supreme Court concluded that Goodspeed did make a deal, which got him leniency in his court cases and received two pardons.

"The disclosure to the jury of Goodspeed's motive for testifying against the defendant might have affected the jury's judgment and put the whole case in a different light," the Supreme Court said.

Robinson maintained he walked into the house, saw the murdered bodies and fled. The high court said that among the witness statements that prosecutors withheld was one from a witness that placed Robinson at the house hours after the murders were committed, according to the prosecution's timeline.

"It is inexplicable that [the prosecution] wouldn't disclose this information but you can only conclude that they thought it would hurt their case," Riach said.

Prosecutors claimed five shots were fired. The high court said prosecutors did not disclose forensic evidence including photographs, ballistics bench notes, sketches and diagrams. A post-conviction expert hired by the defense said the withheld evidence indicated more than five shots were fired and involved two perpetrators.

"Defendant maintains, and we agree that the disclosure of this evidence would have resulted in a weaker case for the state and a stronger case for the defense," the Supreme Court said.

Authorities found "high medium velocity blood splatter" on a coat that matched the DNA of another man, who the defense believes committed the murders. That man, who the Star Tribune is not naming because he hasn't been charged with the murders, had earlier threatened Lambert. Prosecutors did not provide a note about an interview with another man who saw a car leaving the house around 10 a.m., long before Robinson arrived. There was no blood splatter on Robinson's clothes and the small blood spot on Robinson's shoe could have come from Robinson walking into the house where blood was pooled on the floor, the high court observed.

Robinson was told last Friday in a conference call with his attorneys that his conviction and sentence had been reversed.

"He is very pleased that the court made the decision," Carbia said. She said prosecutors have two weeks to ask the state Supreme Court to reconsider its decision. If the decision is upheld, she said, the case would return to the district court for retrial and Robinson, who currently remains in prison, would be transferred to jail.