By CBSLA Staff

LOS ANGELES (CBSLA) — The death sentence of a Santa Clarita woman who murdered her four young daughters in an arson fire more than two decades ago was reversed Monday by the California Supreme Court.

Mother Sandi Nieves in a family photo with her son and four daughters. She took the witness stand in San Fernando court on Monday and denied that she killed her four daughters in their Saugus home last year. They are pictured here in this family photo, along with her. The son, survived. (Photo by David Bohrer/Los Angeles Times via Getty Images)

Sandi Dawn Nieves’ conviction for the killings was upheld, but the court reversed the death sentence “due to the trial court’s misconduct.”

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Nieves was convicted of first-degree murder, attempted murder of her 14-year-old son, and arson and sentenced to death for the July 1, 1998 deaths of 12-year-old Nikolet Amber Nieves, 11-year-old Rashel Hollie Nieves, 7-year-old Kristl Dawn Folden, and 5-year-old Marie Folden. The girls died from inhaling soot, smoke and carbon monoxide. The jury also found true the special circumstance allegations of multiple murders, murder while lying in wait and murder during an arson.

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California’s high court cited the late Superior Court Judge L. Jeffrey Wiatt’s “inappropriate comments throughout the trial” and said they increased in frequency during the penalty phase and “included threats and disparaging comments whose timing interfered with both the opening statement and closing argument for the defense.”

“Ultimately, the trial judge’s conspicuous disdain for defense counsel and witnesses, and his repeated references to their improper or untrustworthy conduct, lent credence to the prosecution’s argument that the defendant was manipulative and deceitful. These were the very characteristics the prosecution highlighted to justify the death penalty,” Chief Justice Tani Gorre Cantil-Sakauye wrote on behalf of the panel in its unanimous ruling. “The trial judge effectively threw ‘the weight of his judicial position’ behind the prosecution’s case and erroneously excluded relevant and potentially beneficial mitigating evidence, thus undermining the defense theory of the case.”

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The Los Angeles County District Attorney’s Office could not be reached for immediate comment on the reversal of the death sentence or whether the trial’s penalty phase would be retried.