SACRAMENTO  (AP) — Gov. Jerry Brown on Friday commuted the sentence of a 52-year-old woman convicted of shaking her baby grandson to death, saying significant doubts surround her conviction.

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Shirley Ree Smith was tearful with relief at the decision, which followed a lengthy court battle that made its way last year to the U.S. Supreme Court.

“I just can’t believe this is finally over with,” she told the Los Angeles Times from Alexandria, Minn., where she now lives with her daughter. “Everybody’s so excited, but I just can’t believe it.”

Smith, who spent eight years and six months in prison, was relieved that she won’t have to resume a possible life sentence in the case that has seen several appeals, said her attorney, Michael J. Brennan.

“She’s been out of custody since 2006 but has been living with this cloud over her head,” he said.

Brown said he was commuting Smith’s second-degree murder sentence to time served “in light of the unusual circumstances in this particular case, the length of time Ms. Smith has served in prison, and the evidence before me that Ms. Smith has been law-abiding since her release from prison.”

Smith was convicted in December 1997 of shaking her 7-week old grandson, Etzel Dean Glass III, to death. Prosecutors argued that she lost her temper on Nov. 30, 1996, when the baby began to cry in her Van Nuys home. She claimed he fell off the couch and hit his head.

An autopsy found a small amount of bleeding on the infant’s brain, and the Los Angeles County coroner’s office said the child died from violent shaking or a forceful blow to the head.

During Smith’s trial, experts testified there were various possible explanations for the death, including shaking, sudden infant death syndrome or an old brain injury that re-bled.

Three medical experts who reviewed the original evidence in order to help Brown concluded there was room for doubt that she had killed the child. If Brown had refused to commute the sentence of 15 years to life, Smith could have faced at least another decade in prison before having a chance at parole, the attorney added.

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Smith has not decided whether to seek a new trial to have her conviction overturned, he said.

The 9th U.S. Circuit Court of Appeals struck down her conviction three times, calling the case a likely miscarriage of justice and saying the evidence at her trial “is simply not the stuff from which reasonable doubt can be established.”

There was no evidence to explain what might have caused Smith to snap, Circuit Judge William Canby Jr. wrote in a 2006 ruling, and it was “extremely unlikely” that she would shake the baby when his mother was a few feet away.

The U.S. Supreme Court last year reinstated Smith’s conviction and ordered her sentence reinstated. Still, the justices said that doubts about whether Smith was guilty were understandable, and that her case might be appropriate for clemency “to help ensure that justice is tempered with mercy.”

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Brown noted that Smith was 37 when she was convicted and had no criminal record.

Smith, her daughter and two grandchildren had moved to Los Angeles from Illinois a few weeks before Etzel was born and were staying with Smith’s sister.

After her release from prison, Smith remained in Los Angeles and at one point was homeless. She eventually chose to leave the state and live with her daughter.

She has no plans to return, her attorney said.

“Her family is in the Minnesota area and she will stay there,” Brennan said. “This place was not a very pleasant experience for her.”

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Brown’s decision was his first sentence commutation since he became governor again in 2011. He granted only one other during his first two terms as governor, from 1975-1980.