(CNN) The high-profile murder trial of Chicago police Officer Jason Van Dyke for his actions in the 2014 killing of 17-year-old Laquan McDonald is in the hands of a jury.
The city, meanwhile, braced for possible demonstrations in a sensational case that already sparked protests.
The panel of eight women and four men -- seven of them white, one black, three Hispanic and one Asian -- will be sequestered during deliberations. They began deliberating Thursday after closing arguments and ended the day without a verdict.
Before Judge Vincent Gaughan dismissed them for the day, jurors requested a transcript of testimony from former Chicago Police Officer Joseph Walsh, Van Dyke's partner the night of McDonald's death.
Van Dyke faces two counts of first-degree murder, 16 counts of aggravated battery and one count of official misconduct for the shooting and killing of the black teenager. The white officer faces up to life in prison if convicted.
Two alternate jurors who were dismissed Thursday said they would have convicted him of murder.
A prosecutor claimed Van Dyke showed no regard for the life of the black teenager while the defense portrayed him as a police veteran ensnared in a tragedy but not a murder.
Assistant special prosecutor Jody Gleason told the jury that Van Dyke contemplated shooting McDonald before he even encountered the young man on the street
"You heard what it was that he said, 'I guess we'll have to shoot him,'" Gleason said, referring to testimony about what Van Dyke told his partner before arriving at the scene.
"It wasn't the knife in Laquan's hand that made the defendant kill him that night. It was his indifference to the value of Laquan's life."
When Van Dyke took the stand Tuesday, Gleason asked about a statement he made to his partner as they approached the shooting scene:"Oh my God, we're going to have to shoot the guy."
"I thought the officers were under attack," Van Dyke said.
Gleason told the jury Thursday, "We know the defendant contemplated the decision to shoot Laquan before he even got out of his vehicle. ... And he never adjusted that mindset."
The prosecutor argued that McDonald was not on trial and that nothing in his "troubled life" could possibly justify Van Dyke's decision to pull the trigger over and over again.
"The defendant knew nothing about him," she said.
A police officer cannot use deadly force merely because a person "will not bow to their authority," she said.
"Just because Laquan McDonald was ignoring him that night he did not have the right to use deadly force," Gleason said.
Defense attorney Daniel Herbert, in his closing, sought to discount a piece of evidence at the center of the case: video of the shooting.
"We have to look at this from Jason Van Dyke's perspective," he said.
He added, "The state wants to watch the last two minutes of this movie without knowing the context."
Herbert said there was no question the case is tragic but it did not amount to murder.
"It's a tragedy that could have been prevented with one simple step," he said. "At any step during that 20-minute rampage -- if Laquan McDonald had dropped that knife -- he would have been here today."
Herbert said it was "unprecedented" for a police officer to face a murder charge for responding to a call and encountering "an individual acting in a strange matter."
"First-degree murder. No motive. No malice. No premeditation," he said. "You can use your common sense, ladies and gentlemen. You can determine what is a murder. This isn't."
The defense rested Wednesday after calling 20 witnesses.
Jurors were instructed Thursday that they could also consider a second-degree murder charge.
Video of the shooting sparked protests, a Justice Department civil rights investigation, criticism of the city's mayor and eventually the ouster of the police superintendent.
Van Dyke is the first Chicago police officer to be charged with first-degree murder since 1980.
Van Dyke told the jury Tuesday that McDonald's face was expressionless -- "his eyes were just bugging out of his head" -- as the teenager kept "advancing" on him, holding a knife.
Standing about 10 to 15 feet away, McDonald "turned his torso towards me," the officer testified.
"He waved the knife from his lower right side, upwards, across his body, towards my left shoulder," the officer said, appearing to get choked up as he demonstrated the action to jurors.
The officer told jurors he then shot McDonald.
Still, McDonald refused his repeated commands to drop the knife, even as he lay wounded, Van Dyke said. McDonald appeared to be trying to get up after the officer stopped shooting, so Van Dyke reloaded -- as he was trained to do -- and fired at the knife, he said.
"I could see him starting to push up with his left hand off the ground. I see his left shoulder start to come up. I still see him holding that knife with his right hand, not letting go of it," Van Dyke said. "His eyes are still bugged out. His face has got no expression on it."
He told jurors: "I just kept on looking at the knife, and I shot at it. I just wanted him to get rid of that knife."
But a prosecutor pointed out inconsistencies in Van Dyke's depiction of the fatal encounter.
The prosecution said Van Dyke fired unnecessarily within six seconds after arriving at the scene, striking McDonald 16 times.
The shooting was captured on a grainy police dashcam video. Van Dyke said he fired in self-defense after McDonald lunged at him with the knife. But the dashcam video -- which a judge ordered the city to release 13 months after the shooting -- showed McDonald walking away from police, rather than charging at them.
During cross-examination, prosecutor Gleason tried to challenge Van Dyke's assertion that McDonald raised the knife.
"You've sat here for several days and watched several videos. ... Have you ever seen Laquan McDonald do that on one of those videos?" Gleason asked.
Van Dyke said the dashcam video and an animated recreation of the shooting presented by the defense didn't show his perspective. But he acknowledged he didn't see McDonald raising the knife in the recreation.
The video shows McDonald walking toward a fence on his right as Van Dyke's squad car pulls up, facing the teenager, to the youth's left.