What are the details?
A Broward County grand jury returned the indictment on Wednesday.
In addition to the 17 murder counts, Cruz has been indicted on 17 counts of attempted murder.
Cruz will face the death penalty if convicted on the murder charges.
According to Florida state law, if Cruz is convicted and a jury unanimously recommends the death penalty, a judge could order his execution.
Florida state law specifies that a person sentenced to death could elect death by electrocution or lethal injection.
Cruz's jailed behavior has been questionable, according to documents obtained by WFTS-TV, which paint an odd picture of the accused mass killer.
The reports allege that Cruz has been seen "laughing" and "giggling" while incarcerated at Fort Lauderdale's Broward County Jail.
The reports also alleges that Cruz has been "contemplative" and "deep in thought," but has been "cooperative."
His frame of mind is described as "logical and coherent."
The reports allegedly span a six-day period, beginning on February 17 — just three days after the deadly school massacre.
At one point, Cruz reportedly asked jail staff to read aloud from the Bible.
Chief Assistant Public Defender Gordon Weekes in a statement said, "They are snippet observations from corrections officers and are not clinical impressions made by his treating psychologist or psychiatrist at the jail."
"They don't show a complete picture," he added. "They are generated because Mr. Cruz has a high-profile case and is on suicide watch."
In addition to being on suicide watch, Cruz is segregated from the rest of the jail population for his own safety, according to the records.
You can watch a video about the report here.