Chicago (CNN) The police shooting of a 17-year-old on a South Side street corner nearly three years ago was captured on five cameras and was unjustified, according to a former investigator who has seen the videos.

Cedrick LaMont Chatman died just feet from the bus stop where his mother caught the bus to work every day. The city's Independent Police Review Authority, which investigates all police-involved shootings, concluded the shooting was justified.

But Lorenzo Davis, the original IPRA supervising investigator on the case, came to the opposite conclusion and says he was fired in July when he refused to change his report.

The video "shows a shooting that should not have occurred," Davis says. "In my point of view, if you do not have to kill a person, then why would you?"

Davis examined the shooting for months and determined it was not justified.

IPRA assigned another investigator and in a new report called Davis "glaringly biased," saying there was a "significant discrepancy" between Davis' findings and "what the facts of the investigation actually show."

Cedrick Chatman, 17, was unarmed and running from police when he was shot.

Five cameras captured all or part of the January 7, 2013, shooting of Chatman: one at a school across the street, two at a food market and two placed atop light poles by police. The school video captured the entire incident, according to court documents.

A federal judge said Wednesday he will rule January 14 whether the videos should be released to the public.

"I know there's a lot of public interest in this, and for good reason," U.S. District Court Judge Robert Gettleman said during a brief hearing. "It certainly informs. ... It's definitely relevant."

The city has fought release of the videos, just as it did in the now-infamous police shooting of 17-year-old Laquan McDonald , who was shot 16 times.

That officer was charged with first-degree murder late last month, the first time since 1968 an on-duty Chicago officer has been charged with murder in a police shooting. The officer's attorney has said his client feared for his life because McDonald resisted arrest and had a knife in his hand.

Facing mounting pressure on police shootings, the city on Monday released video showing another officer shooting 25-year-old Ronald Johnson on October 12, 2014, just eight days before the killing of McDonald. The prosecutor decided not to pursue charges in that case, saying Johnson was armed with a loaded gun and that the officer was not in the wrong to shoot.

The death of Cedrick Chatman occurred more than 20 months before those two killings and raises troubling questions.

In the police account of the shooting, Chatman ditched a stolen car and ran from two officers. As the officers pursued on foot, the 5-foot-7, 133-pound Chatman turned toward them. Officer Kevin Fry told investigators he feared for his partner's life and fired four shots.

Fry said he believed Chatman was armed.

It turned out he was carrying a box containing an iPhone.

"The video supports Officer Fry's observation that (Chatman) was pointing a firearm at Officer Toth," the final IPRA report said, adding that the "use of deadly force was in compliance with Chicago Police Department policy."

Davis said the videos provide a much different account from the police version of the shooting: Chatman was running for his life and never turned toward the officers.

Davis grew up on the gritty South Side and spent two decades as a police officer. He trained future officers on the use of deadly force at the city's police academy. He began working at IPRA in 2008, eventually becoming a supervising investigator in 2010.

"If Officer Fry believed his life was in danger, then his fear was unreasonable," Davis says. "(He) should not have taken this young man's life."

IPRA found Fry justified in the shooting; he remains on the force. He has had 30 complaints lodged against him over the years, including 10 allegations of excessive use of force . The police department found every complaint against Fry to be unwarranted.

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In one case in 2007, Fry and his partner shot a 16-year-old black male in a school alcove after seeing a shiny object around his waist and fearing for their lives. The object wasn't a weapon, but a "shiny belt buckle," according to the IPRA report from the time. The shooting was deemed justifiable, but CNN has learned the city settled with the teen and his family for $99,000. There was no admission of guilt as part of the settlement.

In the case of Chatman, there is one final twist: One of his friends and another acquaintance were charged with his murder. The two weren't even at the scene of the shooting when Fry opened fire.

CNN sought comment from police, IPRA and the prosecutor's office about the Chatman case and the allegations levied by Davis. None of the offices has responded.

A storm brews

The city remains in crisis. Protesters continue to demand justice for Laquan McDonald . Mayor Rahm Emanuel faces questions about his handling of police matters and his leadership.

The accusations of a cover-up grow louder daily.

The mayor fired Police Superintendent Garry McCarthy last week in the fallout from the release of the McDonald video. Emanuel also formed a task force to examine the police department. And on Sunday, he sacked the chief administrator of IPRA.

In Washington, the Justice Department said it is launching its own investigation into the Chicago Police Department to scrutinize the entire force and determine whether police policies play a role in civil rights violations.

CNN analyzed IPRA's officer-involved shooting data and found that 409 people have been shot by police since 2007, a third of them -- 127 -- fatally.

That averages to about one person shot by a police officer every week for the past eight years and a person killed by an officer nearly every three weeks. More than 73% of the people shot were black, the data reveals. Just under 9% of the victims were white and 14% were Hispanic.

Rarely is a police officer found to have used excessive force.

The city has sought to keep allegations of police misconduct out of the public eye. Over the past decade, the city has spent more than half a billion dollars in civil damages and fees in litigation against officers, according to the watchdog Better Government Association.

University of Chicago law professor Craig Futterman fought the city for more than a decade to release tens of thousands of police misconduct complaints and recently won. The city provided him with 56,000 complaints from 2001 to 2008 and from 2011 to 2015; Futterman is still fighting for all complaints dating back to 1968.

The data the city provided showed that the majority of officers each had five or fewer complaints against them. And 10% of officers accounted for nearly 30% of all complaints.

The data also showed only 4% of the complaints were deemed credible; just 2% led to a suspension or firing of an officer.

The data showed that blacks filed 61% of the complaints and whites filed 20%. Of the 4% of complaints deemed valid, 57% are from whites compared with just 24% from blacks.

"If you look at the Chicago Police Department's findings about police brutality and you looked at where they found brutality to exist, it would look like it's a problem with middle-class white people," says Futterman, who played an instrumental role in getting the McDonald video released.

"When the reality is the social status of a victim matters. Blacks are most likely to be abused and the least likely to be believed."

How does that play out in the streets of Chicago?

The neighborhoods with the highest crime rates, Futterman says, are the areas where crimes are least likely to be solved. The trust erodes in those communities while the code of silence among police builds.

And that, he says, is toxic: "The code of silence isn't just about not speaking, it's about controlling the narrative."

Attorney Brian Coffman says that is exactly what happened in the Chatman case; police believed he was another poor black kid on the South Side "whose life is worth nothing."

In addition to seeking release of the videos, Coffman has filed a wrongful death suit against the two officers in federal court. The officers have maintained they followed police protocol in use of deadly force against Chatman.

Coffman disagrees. "He was murdered by police officers," he says. "It raises concerns of safety in Chicago and people that we trust."

A mom at wits' end: 'Doing the best I can'

CNN examined hundreds of pages of court records, deposition transcripts, investigative documents and the autopsy report on the Chatman case for this story. CNN has not yet seen the videos of the shooting.

The documents reveal details of Chatman's young life and the varying accounts of what happened the day he died.

Chatman's father was absent from his life. His mother scraped by, working for $8.25 an hour helping disabled passengers navigate on and off planes at Chicago O'Hare International Airport.

Cedrick was the youngest of four children. He went by the nickname Cello.

He bore the scars of a rough life on the violent South Side. He was shot in the leg walking home from a park swimming pool when he was about 15. He limped for months afterward.

Tattooed across his neck were the names Arianna and Clarence. Arianna was a young girl who was killed in a drive-by shooting while she slept at the Chatman home. Clarence was a cousin killed when he was ejected from a car during a crash.

"You only live once so live it up," said a tattoo on his upper left arm.

His mother, Linda Chatman, tried to make do as best she could. Every Wednesday was movie night and pizza for the single mom and her four children, according to her deposition in the civil case.

She talked with her son about staying out of trouble and keeping away from gangbangers, according to her deposition.

"Be on time, go to school, clean your room and do the household chores" was his mother's motto.

"Don't join the gang," she told him.

"I'm not, Mom," he responded.

He earned $25 every two weeks for doing his household chores. He mowed lawns and did yard work to bring in extra cash. He kept the money in a glass jar.

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The high school junior made B's and C's. He participated in ROTC after school. He had a curfew of 9 p.m. on school nights.

His mother tried to get him to go to other after-school programs, but he wouldn't attend. She often worked 12-hour shifts. She worried about the hours away, because it left plenty of time for a teen to get up to no good.

"I'm a single mom. I'm raising him by myself," she said, according to deposition transcripts. "You know, he's a boy. I'm a female. I'm just doing the best I can do with him."

He got picked up multiple times by police and sent to a juvenile detention center for an array of misdemeanors, including alleged burglary, criminal damage to property and trespassing. His longest stay in a juvenile facility was two months, his mother said. She said he was accused of stealing from a neighbor, but the charges were eventually dropped.

"Why was you doing this?" she said she told him while he was locked up. "I got to constantly keep coming up here."

Cedrick responded: "Mom, I'm going to stop."

Killed at the intersection

Officers Kevin Fry and Lou Toth had a fairly unremarkable day on January 7, 2013, until shortly after 1:30 p.m.

The two veterans were part of the tactical team, a group of plainclothes officers in unmarked cars who focus on crime hot spots.

Toth had been with the unit about three months. He'd spent almost 13 years on the force, almost all of it in gang units. Fry had begun his career as an officer in April 2004 after stints in photography and helping set up lights for a film studio. He spent his first five years on the force with a tactical response unit that gets deployed in marked cars.

Toth and Fry typically had other partners but were paired together this day.

Toth drove the unmarked gray Crown Victoria while Fry monitored the radio and ran checks on the vehicle's computer.

Two 911 calls came into police dispatch at 1:42 p.m. and 1:43 p.m. that a group of teens had attacked the driver of a silver Dodge Charger and that the car's driver fled on foot.

A minute later, the driver of the car called 911 to say he'd been beaten up and "had his car, shoes and wallet stolen." The Dodge Charger had Wisconsin plates, he reported.

Officers Toth and Fry were in the area. They'd seen a vehicle matching that description shortly before hearing of the carjacking. Fry had even run a records check on the vehicle.

But soon, there was a police radio transmission of a battery in progress; then another call of a robbery in progress, "which then was broadcast as a carjacking," Fry said during his deposition.

Toth asked whether the carjacked vehicle had Wisconsin plates.

Yes, he was told.

Toth and Fry sped off in search of the car. They soon spotted it and pulled up next to it.

"This was a felony stop, as we both believed that this car was just taken in a vehicular hijacking," Fry said.

Toth was the first out of the police vehicle, drawing his service weapon and ordering the car's driver to show his hands.

"I ordered the individual in the car to put (his) hands up," Toth told investigators.

Fry got out on the passenger side of the police car, drew his weapon and went around the rear of the police vehicle. He said he heard Toth yell at least three times, "Police, show me your hands."

Toth said Chatman, who was in the driver's seat, reached for something in the car before darting across 75th Street and between two parked cars on the other side of the road. Toth was right on his tail, an estimated 4 feet behind.

Chatman sprinted down a sidewalk. Toth still gave chase, but the teen was getting away as they approached an intersection, according to the officers' account.

Fry pursued from the middle of the street, his Sig Sauer .45-caliber handgun drawn.

"As Mr. Chatman approaches the corner, he makes a slight turn, a subtle turn to the right with his upper body. I see in his right hand a dark gray or black object," Fry said.

"It was a small black object, which I believed to be a handgun."

Asked during his deposition whether the object was ever pointed at the two officers, Fry said, "No."

When Chatman made the slight move to his right with his torso, Fry said he immediately planted both his feet and took a firing position. He did not say anything or give any orders before opening fire.

"I felt his threat was as such that I didn't have time to say anything."

When shots rang out, Toth was still trying to close in on Chatman. "I slowed my pursuit 'cause I didn't know where (the shots) were coming from."

The teenager started to round the corner but had been struck and he crumpled onto the pavement, running into a car as he fell.

Toth said he moved in to handcuff the suspect while he was on the ground. He noticed there wasn't an object in his hands.

Toth told investigators he didn't fire a shot because "I thought I could actually catch him, you know."

But he stood by his partner's actions. "I truly believe," Toth said, "Officer Fry felt as though this individual was armed. ... With his actions of running and began to turn I believe that he was in fear of my life and that's why he just discharged the weapon."

Fry fired a total of four shots. Two struck Chatman, one in his right forearm and the other in the lower right side of his abdomen.

Under further question in his deposition, Fry was asked again, "But he never pointed anything at you or Officer Toth on January 7, 2013, correct?"

Fry: "Correct."

Asked why he fired his weapon, he said, "I was in fear of Officer Toth's life. I was in fear of my own life. And any pedestrians in the area, I was in fear of their life as well."

"And why was that?"

Fry: "Because I believed that the object that he held in his hand was a handgun."

No gun was found at the crime scene.

Chatman had a box containing a new iPhone. It was discovered near his body.

Two men blocks away charged with murder

While her son lay dead in the street, Linda Chatman rode the bus home from work. It took a slight detour because of all the police cars. Chatter on the bus was ominous: "Some boy just got shot! The police just killed a little boy!"

"I'm like, 'That's crazy,'" she said in her deposition. She cussed to herself, thinking, "Somebody is always getting killed around here."

She arrived home to an empty house. She didn't think too much of it at first. But soon a neighbor knocked on the door, asking whether her son was home.

"I'm like, 'No, you know where he is? I've been looking for him.'"

"And she say, 'Oh my God.'"

The neighbor paused, before adding, "I think your son is dead."

Moments later, one of her daughters called from Minnesota. "She said, 'I saw on Facebook, Cedrick dead.'"

The day after her son was killed, she went to police headquarters to try to get a copy of the police report. "They told us they couldn't tell us nothing," she said.

Asked what was her reaction to that, "I can't recall, but I know I was going off."

She went to the coroner's office and identified her son's body. "Just broke down and started crying, like it's true."

She cried for nearly two months. On her arm, she got a tattoo: "Cedrick."

Neither officer was charged in the case. "Insufficient evidence of criminal intent by the officers; complainant had just committed forcible felonies and was fleeing," Lynn McCarthy, the assistant state's attorney, said in deciding not to prosecute.

But two men were charged with first-degree murder in Chatman's killing: his 23-year-old friend Martel Odom and a 22-year-old neighbor, Akeem Clarke.

The two ended up pleading guilty to lesser counts, robbery and unlawful vehicular invasion, and were sentenced to 10 years in prison. In exchange, the murder charges were dropped against both men. The two had each been looking at a minimum of 20 years in prison.

"I do not have the backing of my office to talk about the case," Caroline Glennon, the public defender for Odom, told CNN.

She declined further comment.

Odom and Clarke were accused of participating in the carjacking with Chatman, about 10 blocks away from where the police shooting took place. Fry and Toth told investigators that Chatman was by himself when they came across the Dodge Charger.

The law in Illinois allows for anyone who sets in motion a chain of events that results in the death of another individual to be charged with murder. According to the original charging sheet, prosecutors said Odom and Clarke "without lawful justification committed the offense of robbery ... and during the commission of the offense, they set in motion a chain of events that caused the death of Cedrick Chatman."

Coffman, the attorney representing Chatman's family, says welcome to justice, Chicago-style: "It's almost like a John Grisham movie here."

Davis, who lost his job as a supervising investigator, maintains his belief that the shooting was unjustified and that the videos, if ever released, will prove him correct.

"Deadly force is the last-resort measure. You only use that after you have exhausted all other means of putting somebody in custody," Davis said. "In this particular case, Officer Fry who fired the shots, he did not chase Mr. Chatman. He did not shout a warning. He did not use his radio to give direction of flight. He simply pointed his gun until he had a clear shot. "

The final IPRA report said, "It is not reasonable to suggest what an officer 'should' have done from a reversionary standpoint."

Davis acknowledges Chatman wasn't a saint. But snubbing out his life, he said, isn't justice.