The white Chicago police officer who gunned down Laquan McDonald in 2014 was sentenced on Friday to nearly seven years in prison, bringing an end to a historic case that centered on a shocking dashcam video and fueled the national debate over race and law enforcement.

Jason Van Dyke was convicted last year of second-degree murder and 16 counts of aggravated battery, one for each bullet he fired at the black teenager. He was the first Chicago officer found guilty in an on-duty shooting in a half century and probably the first ever in the shooting of an African American.

Moments before learning the sentence, Van Dyke acknowledged McDonald’s death, telling the judge: “As a God-fearing man and father, I will have to live with this the rest of my life.”

The issue of race has loomed over the case for more than four years, although it was rarely raised at trial. One of the only instances was during opening statements, when the special prosecutor Joseph McMahon told jurors that Van Dyke saw “a black boy walking down the street” who had “the audacity to ignore the police”.

At the sentencing, McDonald’s uncle read a letter written from the teen’s perspective, telling the court that Van Dyke killed him without provocation.

“I am a 17-year-old boy, and I am a victim of murder,” Marvin Hunter said. “I am unable to speak in my own voice” because an officer “thought he would become judge, jury and executioner”.

Chicago police officer who shot black teen 16 times found guilty of murder Read more

In asking for a long sentence, Hunter added: “Why should this person who ended my life forever ... who has never asked for forgiveness ... be free when I am dead for forever?”

Several black motorists testified that Van Dyke used a racial slur and excessive force during traffic stops in the years before the 2014 shooting.

One of those witnesses, Vidale Joy, said Van Dyke used a racial slur after pulling him over in 2005 and at one point put a gun to Joy’s head. He said Van Dyke “looked infuriated” and seemed “out of his mind”. Under cross examination, Joy acknowledged that he did not allege Van Dyke used a slur in his first accounts of the stop.

Another witness, Ed Nance, struggled to maintain his composure as he looked across the room to identify Van Dyke. Testifying about a 2007 traffic stop, he said the officer cursed and slammed him on the car’s hood, grabbed him by the arms and pulled him to the squad car.

Hours later, Van Dyke’s relatives tried to defend and humanize him, saying he was a good father and husband who went out of his way to help and who was not racist.

Van Dyke’s wife said her life had been “a nightmare” since her husband was charged. She said she had been denied a job and her daughter had not been accepted into a dance group because of their last name.

If Van Dyke goes to prison, she said, her biggest fear was that “somebody will kill my husband for something he did as a police officer, something he was trained to do”.

She looked up over her shoulder and addressed the judge directly: “His life is over. Please, please. He has paid the price already ... I beg for the least amount of time.”

During her testimony, Van Dyke wiped his nose and eyes with a tissue while seated at the defense table in a yellow jail jumpsuit.

One of his daughters blamed the media for shaming police officers “for doing their jobs”.

Kaylee Van Dyke, also 17, said the media “twists events, making people create negative thoughts”. She said police officers don’t care about people’s color, “they care about your safety”. She also said she regretted all the times she hadn’t hugged her father.

Van Dyke’s sister, Heidi Kauffunger, told the court that her brother had been abandoned by family and friends since he was charged. She said Van Dyke’s two daughters had been bullied and that the older one even had the words “16 shots” written on her school desk.

Friday’s sentencing came a day after a different judge acquitted three officers accused of trying to conceal what happened to protect Van Dyke.

On Thursday, the Cook county judge Domenica Stephenson cleared the former officer Joseph Walsh, the former detective David March and the officer Thomas Gaffney of charges of obstruction of justice, official misconduct and conspiracy.

Stephenson accepted the argument that jurors in the Van Dyke case rejected: that the video that sparked protests and a federal investigation of the police force was just one perspective of the events that unfolded on the city’s South Side.

The judge said the video showed only one viewpoint of the confrontation between Van Dyke and the teen armed with a small knife. She found no indication the officers tried to hide evidence or made little effort to talk to witnesses.

“The evidence shows just the opposite,” she said. She singled out how they preserved the graphic video at the heart of the case.

The judge in her ruling rejected prosecution arguments that the video demonstrated officers were lying when they described McDonald as moving even after he was shot.

“An officer could have reasonably believed an attack was imminent,” she said. “It was borne out in the video that McDonald continued to move after he fell to the ground” and refused to relinquish a knife.

The video appeared to show the teen collapsing in a heap after the first few shots and moving in large part because bullets kept striking his body for 10 more seconds.

The footage showed Van Dyke opening fire within seconds of getting out of his police SUV and continuing to shoot the teen while he was lying on the street. Police were responding to a report of a male who was breaking into trucks and stealing radios on the South Side.

City Hall released the video to the public in November 2015, 13 months after the shooting, and acted only because a judge ordered it to do so. The charges against Van Dyke were not announced until the day of the video’s release.