Convicted Parkland school shooter Nikolas Cruz returned to court for a surprise post-deliberation hearing Friday after jurors squabbling over whether he should be put to death sent complaints to the judge and prosecutor’s office.

Prosecutors alerted the court Thursday that a juror had received an alleged threat during deliberations and asked for an investigation.

"It may be nothing, but it may be something," Assistant State Attorney Carolyn McCann told the court.

In a letter to the judge, a different juror claimed she was accused by other jurors of deciding on life imprisonment "before the trial started" and never considering the death penalty for the school shooting attack, which left 17 dead on Valentine’s Day in 2018 — a date Cruz said he picked in order to ruin the holiday for the community in perpetuity.

JURY RECOMMENDS PARKLAND SCHOOL SHOOTER NIKOLAS CRUZ GETS LIFE IN PRISON, NOT DEATH PENALTY

Judge Elizabeth Scherer seated in court

Judge Elizabeth Scherer reads the verdict in the trial of Marjory Stoneman Douglas High School shooter Nikolas Cruz at the Broward County Courthouse in Fort Lauderdale, Florida, on Thursday.  (Amy Beth Bennett/South Florida Sun Sentinel/Pool via REUTERS)

"This allegation is untrue, and I maintained my oath to the court that I would be fair and unbiased," the juror wrote.

Florida Judge Elizabeth Scherer also said that two jurors had asked her after the end of the hearing Thursday to speak with her. She said she told them that was not appropriate and thought the matter was over.

However, prosecutor Michael Satz’s office filed a motion to interview a juror after getting a message from one of the jurors claiming she received "what she perceived to be a threat from a fellow juror while in the jury room."

DESANTIS REACTS TO PARKLAND SHOOTER LIFE SENTENCE: ‘YOU DESERVE THE DEATH PENALTY’

Prosecutors said that rather than having the state attorney’s office interview the juror, due to the possibility of a crime having been committed, he wanted police to conduct the interview.

Parkland school shooter Nikolas Cruz looks down in court

Marjory Stoneman Douglas High School shooter Nikolas Cruz sits at the defense table as the verdicts are read in his trial at the Broward County Courthouse in Fort Lauderdale, Florida, on Thursday.  (Amy Beth Bennett/South Florida Sun Sentinel/Pool via REUTERS)

"We are not seeking to set aside the verdict," McCann told the court Friday. "However, the allegation by a juror where they leave a message that they have received what they have perceived to be a threat from a fellow juror in the jury room cannot be ignored. This is a safety issue."

The juror who left the message is not the same juror who sent Scherer the note, McCann added.

The judge said she had given the information to the sheriff’s office and a potential investigation would be up to them.

Cruz, 24, pleaded guilty last year to the murders of 14 students and three staff members at Marjory Stoneman Douglas High School on Feb. 14, 2018.

PARKLAND SHOOTING VICTIM PARENTS FURIOUS AFTER JURY FAILS TO RECOMMEND DEATH PENALTY: ‘I'M DISGUSTED’

Parkland shooting victim parent Fred Guttenberg reacts as he waits for Nikolas Cruz verdict

Fred Guttenberg reacts as he awaits a verdict in the trial of Marjory Stoneman Douglas High School shooter Nikolas Cruz at the Broward County Courthouse in Fort Lauderdale, Florida, on Thursday. Guttenberg's daughter, Jaime, was killed in the 2018 shootings. (Amy Beth Bennett/South Florida Sun-Sentinel via AP, Pool)

The jury failed to reach a unanimous decision, which is required under Florida law for the death penalty.

The victims’ family members and many others, including Gov. Ron DeSantis, had called for the death penalty. 

"This jury failed our families today. But, I will tell you, the monster's going to go to prison. And in prison, I hope and pray he receives the kind of mercy from prisoners that he showed to my daughter and the 16 others," Fred Guttenberg, whose 14-year-old daughter Jaime was killed in the attack, told reporters Thursday. "He is going to go to prison, and he will die in prison. And I will be waiting to read that news on that."

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"I'm disgusted with those jurors," said Dr. Ilan Alhadeff, whose 14-year-old daughter Alyssa was another victim. "I'm disgusted with this system that you can allow 17 dead and 17 others shot and wounded and not give the death penalty. What do we have the death penalty for? What is the purpose of it?"

Fox News’ Julia Musto contributed to this report.