The jury's decision in the case of 43-year-old Michael Gargiulo was read in court Friday afternoon.
In August, the same jurors convicted Gargiulo of the killings including the 2001 murder of Ashley Ellerin on a night she was to go out with actor Ashton Kutcher, who testified at the trial.
The surviving victim and Gargiulo's teenage son were among those who testified in the penalty phase.
Prosecutors also assigned Gargiulo the "Boy Next Door Killer" moniker because he lived near all the victims and watched them.
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