By Ray Sanchez, CNN

(CNN) -- Chicago police Officer Jason Van Dyke was found guilty Friday of second-degree murder in the 2014 fatal shooting of 17-year-old Laquan McDonald.

Van Dyke, who was also found guilty of 16 counts of aggravated battery, sat impassively in a dark suit -- his shoulders slumped -- as the verdicts were read in the high-profile case. At one point, he sipped water from a bottle. He was found not guilty of official misconduct.

His bond was revoked and sentencing was scheduled for October 31. Van Dyke was led out of the courtroom in handcuffs.

Though he was originally charged with first -degree murder, jurors were instructed Thursday that they also could consider second-degree murder.

The panel of eight women and four men -- seven white, one black, three Hispanic and one Asian -- began deliberations Thursday afternoon.

Van Dyke was the first Chicago police officer to be charged with first-degree murder since 1980.

Video of the shooting led to protests, a Justice Department civil rights investigation, criticism of the city's mayor and eventually the ouster of the police superintendent.

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 a 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.

The city has been preparing or possible demonstrations in a high-profile case that already sparked protests.

"The Chicago Police Department has a comprehensive operating plan to ensure public safety in all of our neighborhoods while simultaneously protecting the rights of peaceful demonstrations," police said.

What jurors heard in closing arguments

Before Judge Vincent Gaughan dismissed them for the day Thursday, jurors requested a transcript of testimony from former Officer Joseph Walsh, Van Dyke's partner the night of McDonald's death.

In closing arguments, a prosecutor said 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

"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."

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."

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.