Satz said he filed a "notice of intent to seek death" in the 17 first-degree murder counts stemming from the Feb. 14 rampage at Marjory Stoneman Douglas High School that left 14 students and three adults dead.
Cruz is also charged with attempted murder in the shootings of 17 others who survived.
Cruz is scheduled for an arraignment Wednesday on the murder and attempted murder charges.
Cruz offered to plead guilty to the charges several weeks ago if prosecutors removed the death penalty from the table.
If he does reach a plea deal with prosecutors, the only other option for Cruz is life in prison without the possibility of parole.
The Associated Press contributed to this report.
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