An arrest warrant has been issued for a juror who served on one of the most high-profile homicide trials of the past decade in Colorado, part of an inquiry into possible misconduct that could overturn two separate murder cases and a death sentence.

A judge issued the warrant Feb. 17, after the juror failed to show up for a court appearance where she was to be questioned about her service in the trial 10 years ago. In a court document filed last month, defense attorneys for death row inmate Sir Mario Owens accuse the juror of numerous instances of misconduct during the first of Owens’ two murder trials, including:

Repeatedly lying on her juror questionnaire.

Having an undisclosed friendship with a relative of one of the victims in the case.

Not revealing that she knew members of Owens’ family, which she told a fellow juror after the trial caused her to fear for her safety.

Not disclosing that her son was friends with several witnesses who testified during the trial.

Not revealing that she spoke with one witness at her son’s apartment as the trial was ongoing.

Not disclosing that she personally knew several other witnesses — including at least one who she has since said mouthed the words “Hi, Mom” to her while she sat in the jury box.

The Denver Post obtained the court document through a records request, which the judge overseeing the case granted after hearing debate between prosecutors and defense attorneys.

Jurors are supposed to be impartial, and judges give strict warnings during trials that they are not to have contact with witnesses or attorneys in the case outside of the courtroom. Any contact is supposed to be immediately reported to the judge.

If proved true, these allegations could be enough to overturn Owens’ conviction in the trial, which involved a 2004 murder in Aurora’s Lowry Park. That conviction was used to win a death sentence against Owens in a separate murder trial, which would also be thrown into doubt.

“The number and types of issues that this juror had,” said Christopher Decker, a Denver defense attorney not involved in the cases, “are unlike anything I’ve ever seen in Colorado law.”

Sentences and convictions have been upended in Colorado before based on much less extensive allegations of misconduct. For instance, the death sentence for convicted killer Robert Harlan was overturned in 2005 after it was revealed that jurors consulted a Bible during deliberations. A man accused of killing his wife was granted a new trial in 2014 when it was found that a juror in his first trial had not disclosed on her questionnaire that she was a victim of domestic violence.

Attorneys for Owens declined to comment. In their court motion filed last month, they call the juror’s conduct “extraordinary and egregious.”

Prosecutors at the Arapahoe County District Attorney’s office also declined to comment.

In a written response to the defense’s motion, prosecutors argue that the allegations against the juror “have been thoroughly and repeatedly litigated in previous hearings.” In particular, they argue that Owens’ attorneys failed to prove that the juror’s friendship with a victim’s family member pre-dated the trial. They say the juror listened to the evidence in the Lowry Park trial fairly.

“This juror has come in and testified under oath that the fact she knew a few people who were witnesses did not impact her service in this case,” Ann Tomsic, a chief deputy district attorney in Arapahoe County, said during a hearing on the issue Feb. 17.

The defense’s most recent motion and other court documents show that the juror’s name is Stephanie Griggs. However, she is most commonly referred to in the records by her number: Juror 75.

Owens is one of three inmates on Colorado’s death row, and the cases that put him there were among the most closely watched in the state’s recent history.

In the Lowry Park case, Owens was convicted of first-degree murder in the shooting death of Gregory Vann. That conviction played a significant role for prosecutors in establishing a motive for Owens’ involvement in the 2005 shooting deaths of Javad Marshall-Fields and his fiancée, Vivian Wolfe. Marshall-Fields had been wounded during the earlier shooting that claimed Vann’s life. When he was killed, Marshall-Fields had been scheduled to testify against another man — Robert Ray, who is also on death row — accused of involvement in Vann’s death.

Marshall-Fields’ and Wolfe’s deaths focused attention on threats to witnesses in Colorado and prompted legislation that improved protections. Marshall-Fields’ mother, Rhonda Fields, responded to her son’s death by becoming involved in community activism. She is now a state senator.

On Thursday, Fields said she did not see any signs during the trial of possible jury misconduct and said she doesn’t believe she has ever met Griggs. She said Owens’ attorneys are just doing their job, but it also pains her that debates during the appeals often obscure the lives that were taken.

“I have to let the criminal justice process play out,” she said. “But at the end of the day it’s about murder. And what I want is justice for my son and his fiancée.”

Owens’ and Ray’s murder convictions are still in the early stages of the appeals process — a process that has been marked by controversy.

In 2012, one set of attorneys for Owens began investigating a report of juror misconduct after stumbling across an interview with a juror from the Lowry Park trial. In that interview, the juror said another juror — now identified by defense attorneys as Griggs — said after the trial was over that she “knew Mario’s family” and she “was afraid for her safety because she knew about the people Mario was with.”

Owens’ attorneys dug deeper and turned up what they say are examples of misconduct. For instance, on the questionnaire that Griggs filled out prior to being seated on the jury, she said she had never been convicted of a crime, had no family members who had ever been victims of a crime and had never been involved in a court case. All three of those are false, defense attorneys argue. They also allege that she lied about her educational background.

Further investigation found numerous apparent personal connections to the Lowry Park trial. Griggs’ son has told investigators he was present at the shooting — although it is unclear whether she knew that when she served on the jury. Many of his friends, who had often spent time at Griggs’ house, testified during the trial. She saw one friend at her son’s apartment the afternoon following his testimony.

“Hi, Mom. I saw you today,” the witness is alleged to have said to Griggs, according to the defense motion filed last month.

“I told her, you need to let whoever you need to let know that you need to get off of this, that you’re too close,” Griggs’ son later testified in a post-conviction hearing.

Griggs has testified three times in court so far during the post-conviction process, according to court documents, and has repeatedly said she recognized witnesses during the trial — noting that at least one mouthed the words “Hi, Mom” to her in the courtroom because her son’s friends viewed her like a mother. However, apart from one instance where she told the judge she recognized someone sitting in the courtroom audience, there is no record of her having informed anyone during the trial about her connections to the case, according to the defense’s motion.

In an interview with a police detective after the trial, Griggs said, “Knowing them didn’t weigh on me” and that she listened to evidence fairly. But in court testimony last year, she said she “should have been picked for a different jury or not picked at all.”

Owens’ attorneys argue their client is owed a new trial for Vann’s death. If he is granted one, that would at a minimum put the death penalty case on hold and it would require a new death penalty trial if he is acquitted, said Decker, the defense attorney not involved in the cases.

Even if Owens isn’t granted a new trial for the Lowry Park case, his attorneys say he should still be given a new death penalty trial because the state public defender’s office, which represented Owens in that case, received a tip prior to the death penalty trial about juror misconduct in the earlier case but failed to follow up adequately. That failure means Owens was denied his constitutional right to effective assistance of legal counsel, Owens’ current attorneys say.

Judge Christopher Munch, a retired Jefferson County District Court judge who is now overseeing the first stage of Owens’ appeal, will have to decide what happens next. In the Feb. 17 hearing, he said he worried about the consequences for the justice system if jurors who serve on high-profile cases can expect to have their lives scrutinized during the appeals.

If the misconduct allegations are not true, he said, “What this juror has been put through is extraordinary.”

Owens’ attorney Jonathan Reppucci responded sharply.

“What this juror has put our client through is extraordinary,” he said. “This juror is a fraud.”

There is currently no deadline by which Munch must issue a ruling on the entire appeal, although he could decide soon whether to hold new hearings on the juror issue.

Timeline in the Sir Mario Owens murder cases