A woman who witnessed the fatal police shooting of Laquan McDonald said in a federal lawsuit against the city of Chicago that she was detained by police after the shooting and pressured to change her story, which she had earlier told a freelance photojournalist on video obtained by NBC Chicago.

Alma Benitez filed suit this week, claiming she was illegally detained at a police station shortly after the shooting, her phone confiscated as she was told by officers that her account of what happened in the October 2014 shooting was wrong.

Dashcam video of the 17-year-old's shooting was released last November, prompting nationwide protests, a probe by the US Justice Department and the possible firing of numerous police officers, including Chicago’s police superintendent at the time. Officer Jason Van Dyke, who shot McDonald 16 times as he appeared to walk away from police, has been charged with first-degree murder.

Questions have surrounded the handling of the case since the shooting first happened.

Benitez was interviewed by a freelance photojournalist moments after the incident in 2014, where she recounted what she saw.

“I was in the drive-thru. I was going to place my order when I seen a squad car chasing a guy, an African-American guy,” she said. “There was three squad cars at the moment, but the guy wasn't running fast at all. He was running really slow, and he was trying to pull his pants up. He was holding his pants, but as he was running, he was trying to pull his pants up. After that, I just saw him when, he just stood there. The next thing you know they shot at him.”

Benitez said in the interview she heard several shots before seeing McDonald on the ground. She also noted that she didn’t hear police officers say anything to McDonald before the shooting, though police officers have claimed they made numerous demands telling McDonald to “drop the knife.”

Dashcam video of the shooting had no audio.

"It was super exaggerated,” Benitez said. “You didn't need that many cops to begin with, and second of all, they didn't need to shoot him, they didn't. They basically had him face-to-face. There was no purpose why they had to shoot him."

In her nine-page complaint, Benitez said she tried to take photos and video on her cellphone of what she witnessed. But when police learned of what she was doing, “officers demanded that [Benitez] surrender her phone at the scene of the shooting.”

Later, she was transported to a police station, where she claims she and other witnesses were detained for several hours.

“[Benitez] described to the officers what she saw when she witnessed a Chicago police officer shoot and kill a civilian,” the complaint reads. “Chicago police officers told [Benitez] that her account of what she witnessed was ‘not what really happened’ or words to that effect. Chicago police officers told [Benitez] they had video of the shooting that contradicted her account of what she witnessed.”

The complaint claims video did not contradict Benitez's account and officers later wrote false reports of their interviews with witnesses. It also alleges police "pressured other witnesses being held at Area Central, in a similar manner, to retract their accounts of the shooting."

The complaint cites a longstanding “code of silence” in the police department, alleging officers were attempting to cover up what really happened that night.

It demands a jury trial and seeks an undisclosed amount of compensatory damages.