A man who entered prison as a teenager in 2008 stepped out into sunshine and freedom Wednesday, eight years after a professional hit man told authorities he was responsible for the slayings.

The hit man's first acknowledgement that he was involved came only about two weeks after Davontae Sanford was sent away. But prosecutors repeatedly refused to reopen the case, believing they had already put the right killer behind bars.

Sanford, 23, emerged from a prison in Ionia in western Michigan. He declined to speak to reporters and quickly drove off with a brother and two lawyers for the 130-mile trip back to Detroit.

A day earlier, Sanford's guilty pleas were erased by a judge at the request of prosecutors who conceded the case was compromised by flawed police work.

"I feel blessed," said Sanford's mother, Taminko Sanford, who stayed behind to greet her son at home.

Sanford was 14 — blind in one eye and barely able to read or write — when he was charged with killing four people at a drug den in his neighborhood in 2007. At 15, he pleaded guilty to second-degree murder in the midst of trial and was sentenced to a minimum of 39 years in prison.

The case appeared closed and unremarkable until lawyers discovered the hit man's confession to the same so-called Runyon Street murders, along with eight other killings, just 15 days after Sanford was sent to prison. That touched off years of efforts to get the guilty pleas set aside, but prosecutors resisted at every turn until state police were asked last year to take a fresh look.

The agreement to throw out the convictions doesn't mention the hit man, Vincent Smothers. Instead, prosecutor Kym Worthy said Detroit police — not Sanford — had drawn a diagram of the murder scene. She said that "seriously undermines" the entire case.

Worthy refused to take questions from reporters until a news conference Thursday. For years, her aggressive defense of the case angered Sanford's family and supporters, especially after Smothers offered extensive details about the murders and repeatedly pledged to testify on the young man's behalf.

One of Sanford's lawyers, David Moran of the Innocence Clinic at University of Michigan law school, said it can be difficult for police and prosecutors to accept that a conviction that once appeared airtight is just the opposite.

"It's a human thing," he said.

"There's a tremendous cost when an investigation shuts down and minds close," said Moran, whose staff and students have a long list of victories. "We do encounter tremendous resistance when we present new evidence in actual innocence cases."

At the same time, he praised Worthy for finally recognizing that an "injustice had been done" in Sanford's case.

Margaret Raben, former head of a Michigan association of defense lawyers, said Worthy deserves credit for asking state police to investigate, even after many years.

It's "startling," she said, that Smothers confessed immediately after his arrest but police ignored the admissions.

"They already had this kid," said Raben, who's not involved in the case. "I think they were afraid to ask Smothers more. ... In order for them to do the right thing, they would have had to step up and say, 'We screwed this up the first time.'"

Michigan offers no financial remedy to people wrongly convicted of a crime. But Sanford can sue police over civil rights violations, which is a common practice in these types of cases, Raben said.

Smothers, 35, is in prison for 52 years after pleading guilty in 2010 to eight killings. He said he was regularly hired by drug dealers to kill others in the trade but would never take on someone like Sanford as a sidekick.

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White reported from Detroit.

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