Updated at 9:15 p.m. Sept. 13: Revised to reflect that a jury has been chosen.

Hours before 12 jurors were chosen late Friday for Amber Guyger's murder trial, a defense attorney took a moment to introduce his client.

"This is Amber Guyger," Toby Shook said, moving to stand beside her. "I am proud to represent her, along with the rest of the defense team."

Guyger, a fired Dallas police officer, shot and killed Botham Jean in his home last year after she said she mistook his apartment for her own.

For a handful of candidates in the jury pool, the details of the case were a complete mystery -- and those were just the candidates that attorneys on both sides were looking for.

State District Judge Tammy Kemp, who is presiding over the trial, left the central jury room at the Frank Crowley Courts Building late Friday to call those who were chosen: a dozen jurors and four alternates. Their gender and racial makeup was unclear.

Amber Guyger and Botham Jean (Mesquite Police Department and Instagram)

Earlier in the day, a few hundred potential jurors returned to the courthouse outside downtown Dallas for the first time in a week to be questioned by prosecutors, defense attorneys and the judge about their ability to serve.

Prosecutors and Guyger's attorneys sat up front in the jury room facing jurors. She sat among her attorneys, talking with the defense team and watching the jury pool shrink.

Kemp stood at a podium before the potential jurors and told them the goal is to find a "fair and impartial" jury.

"It only works if you are honest," she said.

Knowledge of the case doesn't preclude a juror from hearing the trial. It's bias that the judge and attorneys on both sides sought to root out.

The jury will be asked to decide whether it was a crime when Guyger, 31, shot Jean on Sept. 6, 2018. If they find that it was a crime, was it murder or a lesser crime like manslaughter or criminally negligent homicide? They could also find Guyger not guilty.

Guyger shot and killed Jean at the South Side Flats apartment building near Dallas police headquarters. She was off-duty but still in uniform when she confused Jean's apartment with her own and mistook him for a burglar, she told investigators. Jean, a 26-year-old accountant from St. Lucia, was shot once.

Testimony is expected to begin Sept. 23, and the trial could last two weeks.

Four thousand potential jurors were summoned to the courthouse last week to fill out questionnaires about their views and knowledge of the case. About 800 showed up.

The remaining 400 would-be jurors filled the second floor outside the Central Jury Room of the Frank Crowley Courts Building on Friday. They stood in several single-file lines as bailiffs slowly allowed them inside.

1 / 2 2 / 2Now-fired Dallas police officer Amber Guyger said Jean's door was unlocked and ajar and that she entered his apartment thinking it was hers and mistook him for a burglar. Jean had a red mat in front of his door. Guyger did not. Jean's family says he would not have left his door open and unlocked.(Jennifer Emily / Staff)

For the jurors selected, Kemp said, the trial won't be anything like the courtroom dramas they see on TV.

"We are not at all like Perry Mason. We are not at all like Law & Order," she said. "Set aside your preconceived notions."

Jurors may be sequestered during the entire trial and will not be able to use their phones or access the internet. The trial could last two weeks, Kemp said, but may be shorter or longer.

Attorneys spent the past week going through juror questionnaires. Some of those called to serve will be eliminated based on their answers. The remainder faced questioning by attorneys on both sides.

An unlimited number of jurors can be dismissed "for cause," meaning they say they can't follow the law or set aside opinions they have about the case. The defense and the prosecution also have 10 peremptory challenges they can use to dismiss jurors for any reason except race and gender.

1 / 2 2 / 2Now-fired Dallas police officer Amber Guyger said Jean's door was unlocked and ajar and that she entered his apartment thinking it was hers and mistook him for a burglar. Jean had a red mat in front of his door. Guyger did not. Jean's family says he would not have left his door open and unlocked.(Jennifer Emily / Staff)

Kemp hoped to select 12 jurors and four alternates by the end of the day Friday. Usually, only one or two alternates are chosen. Alternate jurors listen to all the testimony but only deliberate if one of the original 12 jurors can't serve.

During jury selection, prosecutor Jason Fine asked 220 potential jurors how many had never heard of the case. About 10 raised their hands.

Jurors raised paper numbers hung from the backs of their chairs to answer Fine's questions.

Juror 46 couldn't convict Guyger of murder no matter what the evidence said. Neither could jurors 6, 10, 53, 88, 92, 119 and 181. Juror 14 said he was biased in favor of the police. Juror 179 said she couldn't sit in judgment of someone.

Juror 75 told Fine that she didn't understand enough about the case to answer his questions.

"You know what, No. 75?" Fine responded. "You're actually a perfect juror right now."

Amid laughter from the jury pool, someone yelled, "One down!"

(Juror 75 did not make the jury.)

State District Judge Tammy Kemp is presiding over Amber Guyger's murder trial. (Ryan Michalesko / Staff Photographer)

Kemp gave each side two hours to talk with jurors.

The judge sent the members of the jury pool home around 7:30 p.m., telling them she'd call them to let them know if they'd been chosen.

The attorneys reconvened with Kemp about an hour later to discuss who they wanted to strike from the panel, and the jury was chosen just before 9 p.m.

Kemp still needed to officially rule that the trial would remain in Dallas County.

Guyger's defense attorneys had asked Kemp to move the trial to another county in North Texas. They said she can't receive a fair trial in Dallas because of widespread publicity. Prosecutors objected, and Kemp said she would see whether a jury could be seated before she ruled on moving the trial.

Guyger's attorneys wrote in a motion seeking a change of venue that "media hysteria" surrounding the case has been prejudicial. They want court proceedings to be moved to one of six counties: Collin, Ellis, Fannin, Grayson, Kaufman or Rockwall.

An analysis by The Dallas Morning News found that Guyger probably would face a jury that is whiter and more conservative if her trial were moved to one of those counties.

Read more about Botham Jean and Amber Guyger.