What to Know Van Dyke is charged with murder in the shooting death of 17-year-old McDonald nearly four years ago

The Chicago police officer was captured on dashcam video shooting McDonald 16 times the night of Oct. 20, 2014, on the city's Southwest Side

Van Dyke entered a plea of not guilty

As the trial for Chicago Police Officer Jason Van Dyke entered its second day, jurors heard dramatic testimony from the officer's partner, who detailed the moments before the shooting unfolded.

Joseph Walsh, who faces charges for falsifying his report, testified off camera and under immunity, that he believed Laquan McDonald to be a danger before the shoting.

The testimony contradicts statements made by previous officers called in the case.

"I assessed the entire incident when he was on the ground," Walsh said. "He was a threat, still armed... with a knife in his hand... still moving."

Another witness called Tuesday, however, said he saw no "threatening movements" while McDonald was on the ground.

Van Dyke has claimed he opened fire that night to protect himself and other officers. The Chicago police officer is charged with murder after he shot McDonald 16 times the night of Oct. 20, 2014, on the city's Southwest Side.

Walsh said that he and other officers wanted to stop the knife-wielding McDonald from entering a Burger King or a Dunkin Donuts near the scene of the shooting.

Opening statements had only just begun Monday when the widely circulated dashcam video showing the fatal shooting of McDonald was played in court.

"From the time [Van Dyke] gets out [of the squad car], six seconds later, he starts to shoot," special prosecutor Joseph McMahon told the 12 jurors and five alternates. "For the next 12 and a half seconds, he continues to pull his trigger over and over until his whole clip is emptied on Laquan McDonald."

Van Dyke's attorneys maintain the Chicago officer has been wrongly charged, saying he was acting within the law when he shot the teen, who at the time was an armed felon fleeing a crime scene.

3:45 p.m.: Day 2 of testimony is complete in Jason Van Dyke trial. Jurors heard from 9 witnesses today, including, Joe Walsh, Van Dyke’s partner on the night Laquan McDonald was killed.

3:22 p.m.: Judge Gaughan strikes ALL of the testimony from FBI forensic expert, Mark Messick, because he’s not a ballistic expert and could not clarify if the green arrows on FBI video show the puffs of smoke came from bullets hitting the ground or bullets that struck Laquan’s body.

2:54 p.m.: The 12 jurors in Jason Van Dyke trial are now watching FBI enhanced dash cam video of the shooting. This is now the 5th witness today, in which the video has been played for them to see the shooting.

2:04 p.m.: Jurors are now getting a chance to see Jason Van Dyke’s duty weapon, a Smith and Wesson 9mm semi-automatic that holds 16 rounds.

2 p.m.: Jurors are now getting a chance to see Jason Van Dyke’s duty weapon, a Smith and Wesson 9mm semi-automatic that holds 16 rounds.

1:42 p.m.: A second evidence video viewed, was filmed at the hospital where Laquan McDonald was pronounced dead. The jury saw his blood stained clothes filled with bullet holes.

1:30 p.m.: The jury is now watching video taken of the crime scene, by a CPD evidence tech for crime scene investigation unit. It shows the 16 cartridge casings, blood on the pavement and the knife Laquan McDonald was holding

12:20 p.m.: Next witness, Cook County Police Officer Adam Murphy, tried to give aid to Laquan McDonald while he laid on the ground. He could hear him gasping for air and gurgling. Told him an ambulance was on the way, but the gasping and gurgling from Laquan "stopped shortly after."

12:10 p.m.: CPD Officer David Ivankovich and his partner, answered the dispatch call for a taser that night in 2014, but by the time they arrived on the scene at 42nd and Pulaski, Laquan was already shot and lying in the middle of the street.

11:40 a.m.: Next witness, Xavier Torres, was in a car on Pulaski and witnessed the Laquan McDonald shooting. Testifies he did not see Laquan making any threatening movements. That he didn’t make movements towards officers on the scene “looked like trying to get away from the officers”.

11:22 a.m.: Joe Walsh, Van Dyke’s former partner, completes his testimony. He still faces trial for his own charges stemming from that night. He’s accused of filing a false report, exaggerating the threat Laquan McDonald posed.

11:12 a.m.: Walsh describes the moments before the shooting. "He was on that diagonal...swinging the knife. He turns and looks directly in our direction with a stare and a focus beyond us.That’s when I believed the first shot occurred...when he turned his right shoulder."

11 a.m.: Prosecutor Joseph Cullen: “Did you find Laquan McDonald to be a danger at any point?”

Joe Walsh: “Yes. I assessed the entire incident when he was on the ground. He was a threat, still armed...with a knife in his hand..still moving."

10:10 a.m.: Day two of testimony in the Jason Van Dyke trial begins with one of the most important witnesses, Joe Walsh, Van Dykes partner that night. Walsh has an immunity deal, so his testimony can not be seen or heard by anyone outside of the courtroom.