The sentencing is still under way and more details are expected to be released shortly.
Earlier, a woman fainted inside the Sydney courtroom and was carried out by court officers.
Justice Megan Latham paused in her remarks on the sentence of Roger Dean after a woman, believed to be a relative of one of the victims, collapsed in the packed Sydney court room.
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Dean is being sentenced over the murder of 11 elderly nursing home residents who perished in a fire he started on November 18, 2011.
Dozens of relatives gathered in the Supreme Court for the sentence, some wearing pins bearing photographs of their loved ones.
