(CNN) Elgin, Illinois, police officers tried for more than an hour to get a woman they believed was suicidal and possibly armed with a steak knife out of her car on the side of Interstate 90, including threatening her with arrest.
Authorities say she refused, and at one point she set something on fire and threw it into the back seat. As smoke filled the car, police moved toward it to force her out. But she opened the door, choking on the smoke, and got out of the car as three gunshots rang out. Police say she had a knife in her left hand, but it's not clear in the video.
Decynthia Clements, 34, was killed, and her family wants answers.
Elgin Police Chief Jeff Swoboda is trying to provide some information with the release Thursday of about 30 hours of video from police body cameras at the scene. It's an effort to be transparent, he said in a news conference.
"We are trying to lead the way in what a transparent police department looks like," Swoboda told reporters. "And what a transparent police department looks like is that you get in front of the cameras and you talk with the people before you have all the answers."
An attorney for her family told CNN that Clements was emotionally disturbed and the situation should have been handled differently.
The Illinois State Police is leading an investigation into the March 12 shooting, the police chief said. The Cook County state's attorney will review the case when it is completed, but the process is expected to take months, Swoboda said. The police department also will conduct an internal investigation to determine whether its policies were properly followed.
At the news conference, police showed a video about 20 minutes long, compiled from different cameras and angles and meant to establish a narrative of the shooting. Clements' family watched the video before it was released Thursday, Swoboda told reporters.
In the footage, police are seen trying to get Clements to exit her vehicle, which is stopped on the shoulder of I-90 in Elgin, about 40 miles west of Chicago. She periodically tries to drive away, but her car is missing two tires and can be heard scraping against the pavement. As more officers arrive, one tells them he saw Clements with a steak knife and a "white powdery substance" on her hand, which he assumes to be crack cocaine.
Officers discuss strategies to get Clements -- whom they believe to be suicidal -- out of the car. They repeatedly tell her she is under arrest, but she refuses to get out. Eventually police close the interstate as a safety precaution.
Police continue to talk tactics. One officer says if Clements exits the vehicle with the knife, they will try to stop her. But if she has the knife to herself, he says, "we're not going to end it for her." Officers discuss using multiple methods of nonlethal force, including Tasers and rubber bullets.
At this point, Swoboda said, police have spent an hour on I-90 trying to get her out of the car.
Officers pin Clements' vehicle between two squad cars in an attempt to keep her from leaving. But a sense of urgency takes over after she lights something on fire and throws it in the back seat of her vehicle, which begins filling with smoke.
When a fire erupts inside the vehicle, officers decide to extract her from the car. One can be seen removing his Taser from its holster before several officers approach. From the body camera, the car door can be seen opening, and Clements is heard choking on smoke, billowing out of the top of the car.
Officers again tell her to exit the vehicle, and Clements steps out and moves toward the officers, when one of them fires his weapon three times. Police say she was holding a knife.
Antonio Romanucci, an attorney for Clements' family, told CNN in an interview Friday that police had "no reason" to open fire.
"There was no evidence that police were in fear of their own bodily harm," Romanucci said, adding it's clear in the video that officers saw she was "clearly emotionally disturbed."
Romanucci believes the situation should have been handled differently, and that a crisis intervention team should have been on scene. "Since they did not deal with this as a medical situation, they dealt with this as a militarized, police situation," he said. "Because one officer perceived her as deadly threat, despite the plan not to kill her, with all those officers there, it was predetermined that she would die."
Swoboda said in the Thursday news conference that one of the officers on scene led the department's hostage negotiation team until recently, and that a "high percentage" of Elgin police officers have crisis intervention training.
"The family is grieving right now," Romanucci told CNN. Clements, he said, will be buried Saturday.
"We hope the right thing is done," he said. "We hope the investigation is transparent. And hope they find that this officer was not justified in using deadly force."
Swoboda said his department wanted to begin the healing process and chose to release the video now, though he recognizes it will initially cause more pain for the family.
"It's cases like this though that also force some tough conversations," he said. "And I want the community to know that the Elgin Police Department is ready to have those tough conversations."