A 12-person jury in the sentencing trial of the Parkland school shooter is expected to begin deliberations Wednesday on whether to recommend the death penalty.

Broward Circuit Judge Elizabeth Scherer said the jury will be sequestered during their deliberations.

Should jurors recommend the death sentence, their decision must be unanimous, or Nikolas Cruz will receive life in prison without the possibility of parole. If the jury does recommend death, the final decision rests with Judge Scherer, who could choose to follow the recommendation or sentence Cruz to life.

Cruz has pleaded guilty to 17 counts of murder and 17 counts of attempted murder in connection with the February 2018 shooting at Marjory Stoneman Douglas High School, in which . The massacre is at a US high school. In the years since the shooting, survivors and victims' families became .

Because Cruz pleaded guilty to all counts, the trial phase was skipped and the court went directly to the sentencing phase.

Closing arguments in the sentencing trial took place Tuesday, with the defense and prosecution each allotted two and a half hours to make their closing remarks. Prosecutors argued Cruz's decision to commit the shooting was premeditated and calculated, while Cruz's defense attorneys offered evidence of a lifetime of struggles at home and in school.

"What he wanted to do, what his plan was and what he did, was to murder children at school and their caretakers," lead prosecutor Michael Satz said Tuesday. "The appropriate sentence for Nikolas Cruz is the death penalty," he concluded.

However, defense attorney Melisa McNeill said Cruz "is a brain damaged, broken, mentally ill person, through no fault of his own." She pointed to the defense's that Cruz's mother while his mother was pregnant with him, saying he was "poisoned" in her womb.

"And in a civilized humane society, do we kill brain damaged, mentally ill, broken people?" McNeill asked Tuesday. "Do we? I hope not."

Jury selection for the lengthy trial began in early April, with taking place in July. Throughout the last three months, prosecutors and defense attorneys have presented evidence of aggravating factors and mitigating circumstances, reasons Cruz should or should not be put to death.

As part of the prosecution's case, family members of the victims were given the opportunity over the summer to take the stand and offer raw, emotional testimony about how Cruz's actions had forever changed their lives. At one point, even members of Cruz's defense team were brought to tears.

The defense's case came to an unexpected halt last month when -- having called just 26 of 80 planned witnesses -- , leading the judge to admonish the team for what she said was unprofessionalism, resulting in a courtroom squabble between her and the defense (the jury was not present).

Defense attorneys would later file a motion to disqualify the judge for her comments, arguing in part they suggested the judge was not impartial and Cruz's right to a fair trial had been undermined. Prosecutors disagreed, writing "judicial comments, even of a critical or hostile nature, are not grounds for disqualification."

Scherer ultimately denied the motion.