CHICAGO >> The gunshots blasted on and on, 45 in all, until Calvin Cross lay dead in a vacant lot. Cross, 19, had run away after three Chicago police officers pulled alongside him on a South Side street near his house. Bullets hit his chest, arm, back, face and the little finger on his right hand.

The officers, who fired four weapons including an assault rifle that night in May 2011, said Cross had fired at them. Investigators found an old revolver several hundred feet from Cross’ path. But tests later showed definitively that the gun was inoperable and did not have Cross’ fingerprints.

Among the officers, part of a special unit that some have accused of aggressive stops and illegal searches and that has since been disbanded, there have been 17 complaints over the years, but none led to discipline. The three were cleared of wrongdoing in Cross’ death, too, and returned to duty.

Nevertheless, the city this year paid Cross’ family $2 million after relatives filed a wrongful-death suit.

“One officer reloaded and another one shot at him with two different guns,” Dana Cross said of her son’s shooting, which she heard from inside her house. “I want to know why those officers are still working.”

The release last month of a 2014 video showing a Chicago police officer fatally shooting another teenager, Laquan McDonald, has upended this city. The police superintendent, Garry F. McCarthy, was forced out, despite having overseen a reduction in crime citywide. So was the leader of an authority charged with disciplining officers. The Justice Department has opened an investigation into possible civil rights abuses by the department. Demonstrators call nearly every day for Mayor Rahm Emanuel to resign.

But the Chicago Police Department’s record of brutality began long before McDonald, 17, lay crumpled on Pulaski Road. For decades — back to violent clashes at the Democratic National Convention of 1968 and the confessions coerced by a “midnight crew” of detectives accused of using suffocation, electric shock and Russian roulette on black men in the 1970s and 1980s — the Chicago police have wrestled with allegations of torture, racism, weak oversight and a code of silence.

“There is a problem in the city of Chicago when an officer who was sworn to serve and protect can gun down a citizen for no other reason than that he was black,” the Rev. Marvin Hunter, who was McDonald’s great-uncle, said last week at his church on the West Side. “Laquan McDonald represents thousands of Laquan McDonalds — same black skin, same poverty, same social and economic injustice that is put upon them, but with different names and different ages.”

In Chicago, the nation’s third-largest city, officers shot and killed 70 people, most of them black, in a five-year span ending in 2014. That was more fatal police shootings than in any of the nation’s nine other largest cities during the same period, according to the Better Government Association, a nonprofit watchdog organization.

The Chicago Police Department has also been known for issuing little or no punishment to its own, even after a 2007 overhaul of its discipline system that was portrayed as creating a tough, autonomous authority.

Yet under that new system, the vast majority of complaints against police still do not result in discipline. Of more than 400 police shootings since the new Independent Police Review Authority was created, the agency has found valid claims of wrongdoing against officers in only two cases. The authority issues only recommendations for discipline. The police superintendent and the Police Board have the last word in the most egregious cases.

All the while, the city, which is in the middle of a fiscal crisis, spent more than $500 million settling police cases since 2004.

In defending the department, a police union official said that police seemed to have become “the new doormat” for a city that has witnessed surges of bloodshed as gangs have splintered and guns proliferated.

Dean Angelo Sr., president of the union representing Chicago’s rank-and-file officers, said that officers take thousands of guns off Chicago’s streets each year. That there have not been more shootings, he said, indicates that officers are showing restraint. This year, Chicago police have seized 6,714 illegal guns as of Monday, more than last year during the same period.

“That is good policing,” Angelo said. “But nobody looks at it that way.” He added: “The same politicians that are throwing us under the bus were banging our door down to get our endorsement when they were running for office.”

Emanuel has apologized for McDonald’s death and appointed a task force to re-examine the department, the city’s oversight of officers and its practice of keeping evidence secret during investigations.

“We need a painful but honest reckoning of what went wrong, not just in this one instance but over decades,” Emanuel said in an emotional speech last week.

Yet Craig B. Futterman, a professor at the University of Chicago Law School who has studied the police here and fought to make discipline records public, said he sensed a “familiar playbook.”

“Heads will roll and we’ll form a blue ribbon commission to study the problem,” Futterman said. “But after each and every one of these scandals, we’ve never had the political courage to address the underlying issues, the very causes of distrust between the black community and the Chicago police. Police officers here have been allowed to abuse the most vulnerable Chicago residents with near impunity.”

‘He was running away’

Cedrick Chatman was behind the wheel of a Dodge Charger that had been reported carjacked when two plainclothes officers pulled up beside him one afternoon at a South Side intersection. They ordered him out at gunpoint. Chatman, 17, ran. He was carrying an iPhone box, and the officer who shot and killed him said he thought the box was a gun.

Lorenzo Davis, a retired 23-year veteran of the Chicago police, supervised an investigation into that January 2013 shooting as part of his second career — scrutinizing excessive force complaints for the Independent Police Review Authority. The shooting, Davis concluded, was unnecessary.

“He was running away so why kill him?” Davis said in an interview.

Davis, a former police commander, told his supervisors as much in a 2014 report recommending that the officer, Kevin Fry, be fired. But Davis said the top echelon of the authority disagreed, ordered him to change his finding and — not long after he refused — fired him. A new report, written by another investigator, came out this year: The authority said that the officer followed departmental guidelines when he shot Chatman.

Davis, who has filed a wrongful termination suit, said that his superiors tried to push him to soften his findings in six cases, including the Chatman shooting, and that the authority fails to live up to the very reason it was created: independence.

“It goes wrong because there’s a culture there where the investigators and supervisors for the most part feel that police officers always tell the truth and that quite often the complainants embellish or do not tell the truth,” Davis said.

A spokesman for the authority declined to comment on Davis’ claims or the Chatman case, citing continuing litigation. Scott Ando, the authority’s chief administrator, whose dismissal was announced by Emanuel this month, denied suggestions that he had protected the police.

“I did my job fairly and objectively at all times,” Ando said in an interview.

The Chicago Police Department is the nation’s second-largest city force, with an annual budget of about $1.3 billion and about 12,000 officers, a number it hopes to expand to as many as 13,000. While the city’s population is split almost evenly among black, white and Hispanic residents, more than half of the officers are white, about 22 percent are black and 22 percent Hispanic, police officials said.

For years, claims of police brutality were handled by the Office of Professional Standards, an internal unit that was widely criticized for its lack of independence.

By 2007, the department was engulfed in scandal over a surveillance video that showed a drunken officer, Anthony Abbate, beating a female bartender, and allegations that fellow officers covered up for him. That year, Emanuel’s predecessor, Mayor Richard M. Daley, announced creation of the Independent Police Review Authority — run by civilians and overseen by the mayor — to replace the Office of Professional Standards.

Now the new system is accused of being little better than the old. From 2011 to 2015, 97 percent of more than 28,500 citizen complaints resulted in no officer being punished, according to data recently released by the Invisible Institute, a nonprofit journalism organization, and the Mandel Legal Aid Clinic of the University of Chicago Law School. The Police Department and the review authority have questioned the data, though Emanuel said last week that the low rates of disciplinary action “defy credibility.”

The independent authority’s final report on the Chatman shooting backed the officers’ versions of events: that when they stopped Chatman, they had reason to believe he might be armed and might have committed a felony because of a radio call saying that the vehicle had been carjacked.

As Chatman got out of the car, he reached toward the floor, causing one officer to assume he was grabbing a weapon. As he fled, Fry said that he saw a dark object in Chatman’s hand and that he saw him turning slightly, at which point the officer fired four times, hitting him twice.

Facing a wrongful-death lawsuit brought by Linda Chatman, his mother, the city obtained a protective order barring release of surveillance video that captured the shooting. The city had also fought release of video in McDonald’s case for many months, citing investigations. Chatman’s lawyer, Brian Coffman, has asked a federal judge to reconsider and allow the video’s release.

Davis, the former authority supervisor, was able to watch those videos before concluding that the shooting was wrong. He said the images, if they become public, would back up his view.

“He waited until he had a clear shot and then he took one,” Davis said of Fry.

An inoperable gun

On the night he died, Calvin Cross and a friend, Ryan Cornell, were two blocks from Cross’ house when a police cruiser slowed after the officers saw him “making movements with his hands and body” that suggested he had a gun, a police report said.

The officers — Mohammed Ali, Macario Chavez and Matilde Ocampo — were members of the Mobile Strike Force Unit, tasked with making gun and drug arrests in high crime areas, including Cross’ West Pullman neighborhood. Chavez, 29, and Ocampo, 35, ordered Cross and Cornell to show their hands, according to the report. Cornell, who had been stopped numerous times by the police, complied. But Cross, whose mother said her son’s only previous brush with the law was for violating an 11 p.m. curfew, ran.

“I said, ‘Oh, my God,’” Dana Cross said of the moment she heard the shots. “It was so close. It was right around the corner.”

She said her son had returned home from a Job Corps program in southern Illinois, where he had earned a certificate for bricklaying, because he had learned his girlfriend was pregnant with a boy.

“He was real excited about that,” said Dana Cross, who hated guns so much that she had forbidden him from playing with water pistols.

Two of the officers said that Calvin Cross fired three shots as he broke into a sprint. Chavez opened fire with the department-issued assault rifle he kept strapped to his chest and Ocampo shot at the fleeing Cross with his 9-mm semi-automatic pistol. The staccato bursts from their weapons sliced into trees and parked cars.

The officers found Cross lying among bushes in a vacant lot. When he moved, but failed to show his hands, Chavez said he fired three more times with his assault rifle — emptying his clip with shots 26, 27 and 28. He then switched to his 9-mm Beretta and fired three more times. Ali also reloaded and fired at Cross as he lay prone. In all, they fired 45 times.

The shot that killed Cross struck him in the face, between his nose and his right eye, according to the medical examiner’s report.

A gun found several hundred feet from Cross’ path was a fully loaded six-shot Smith & Wesson revolver that had not been fired and was so full of dirt that the Illinois state police lab deemed it inoperable. There were no fingerprints on the gun, and Cross’ hands had no gunshot residue.

Despite those inconsistencies, the Independent Police Review Authority’s investigation concluded Cross was armed. Its final report found Cross’ killing was justified because “the officers were reasonable in their fear” that Cross “posed a threat.”

Eighteen months after the authority completed its investigation, the city approved a $2 million payment to the family this year, one of a number of cases in which the city has settled claims even when officers have been cleared.

In one such case, the family of Joshua Madison, 21, an unarmed black man killed by a Chicago police officer in 2010, received a $1 million settlement in June. Before the settlement, Robert Campbell, the officer acknowledged in a deposition that he had an alcohol problem. Two weeks after the deposition, Campbell, 33, committed suicide.

City officials also paid Laquan McDonald’s family $5 million months before the officer who shot him was charged with murder and before the rest of Chicago saw the video. Jason Van Dyke, the officer who has been indicted on six counts of murder and a count of official misconduct in McDonald’s death, was to appear in court here Friday.

“The Department of Law has a responsibility to taxpayers to weigh many factors when proposing to settle any case,” Bill McCaffrey, a spokesman for the city’s law department, said. “While this may include the determination of the Independent Police Review Authority, it will also include how a jury is likely to react to the evidence, the probability a jury may find against the city and the financial exposure to taxpayers.”

After Cross’ death, the officers who shot him returned to duty. Ali has since accumulated 11 citizens’ complaints, including complaints for improper use of force and conducting illegal searches. Chavez, who fired 31 of the 45 shots, has had a total of four complaints, including two for unnecessary use of force. And Ocampo has had one complaint, for an illegal search. None of the complaints has led to departmental discipline.

Cross, pointing out that Chavez and Ali had been accused of using unnecessary force two weeks before her son was killed, said that the department had failed to adequately investigate and punish officers.

“If the police had taken care of business then,” she said, “my son would still be alive.”