(CNN) -- When Minneapolis-based activist Michelle Gross learned the name of the officer who planted his knee on the neck of George Floyd until after he lost consciousness, she wasn't surprised.
Gross, who has tracked 20 years' worth of complaints against Minneapolis police, identified the officer by cross-checking the badge number seen in the video of Floyd's death against her records. It belonged to Derek Chauvin -- a familiar name.
"When I saw the name I said, 'Oh, him,'" Gross told CNN. "When you start to see those same officers over and over again with multiple complaints, their names lodge in your brain."
Gross, of the non-profit Communities United Against Police Brutality, argues that Chauvin -- who had 18 prior complaints filed against him and received reprimands for only two of them -- exemplifies the way problematic officers repeatedly thwart accountability in Minneapolis.
Minneapolis Police Chief Medaria Arradondo outlined a vision for change at a press conference on Wednesday, saying that he was withdrawing from contract negotiations with the police union, which he suggested has constrained reform. The city's own data shows how rare disciplinary action has been for years within the department that Arradondo and other reform-minded chiefs have headed.
Only about 1.5% of complaints filed against Minneapolis police have resulted in suspensions, terminations or demotions between 2013 and 2019, according to a CNN analysis of data from the city's Office of Police Conduct Review, which investigates complaints. That office, which is separate from the police department but works with officers to resolve complaints, received about 2,013 complaints against police within its jurisdiction in that time.
If complaints that garnered letters of reprimand are included, that rate of discipline rises to about 2.6%.
While no national data exists on the outcome of police complaints filed across the country, former law enforcement officials and oversight organizations agreed that the ratio of complaints filed to officers disciplined in Minneapolis seems low.
Liana Perez, the director of operations for the National Association for Civilian Oversight of Law Enforcement, an organization whose members include police oversight agencies, said percentages vary widely between departments, which use different metrics, but that the average "sustain rate" for complaints is usually between 5 and 10%.
Andrew Hawkins, of the Minneapolis Department of Civil Rights, which houses the conduct review office, said a majority of complaints against officers allege lower-level violations that are not eligible for discipline and that such complaints are instead eligible for coaching, training and mediation.
Hawkins said that if complaints that result in coaching are included, then 18.5% of complaints against Minneapolis police between 2013 and 2019 have ended with some form of corrective action.
Coaching, however, is not considered a form of discipline, Hawkins said, and state law prohibits the disclosure of which specific cases ended with coaching. From the public's perspective, cases closed with coaching show "no discipline." And the city's current contract with the police union states that investigations into employee conduct that do not result in discipline "shall not be entered into the employee's official personnel file."
Janee Harteau, who was the city's police chief from 2012 to 2017, said she is not opposed to coaching, but she said omitting complaints closed with coaching from personnel records obstructed her ability to understand whether certain officers had patterns of misconduct.
"I can use the analogy of someone who speeds all the time. If you get pulled over and don't have speeding on your record, the officer thinks you don't speed all the time, you know: 'I'll give you a warning, don't do it again.' And then they get pulled over again, and the same thing. But once someone has that on their record, it cues you up that, hey, this isn't your first time that you've been speeding."
She described the current discipline system as "ineffective."
"What we do know is these systems are not set up to be efficient. They change very slowly. Leadership comes and goes and unions stay," said Harteau, who described the city's police union as an "impediment" to change.
"This mess today"
Police Chief Arradondo said Wednesday that his department would integrate new data systems to enable department leaders to intervene after early warning signs of misconduct.
He expressed frustration with the union contract, parts of which he said make his job "difficult."
"There is nothing more debilitating to a chief" from an employment perspective than having grounds to terminate an officer for misconduct but not being able to because of "a third-party mechanism," Arradondo said.
In a statement, the union, the Police Officers Federation of Minneapolis, called on the chief and the city's mayor to return to contract negotiations. The union has always welcomed the opportunity "to set clear expectations, train employees as to those expectations, and improve accountability for both officers and supervisors who fail to conduct themselves accordingly," it read in part.
Michelle Gross, the activist, said her organization has repeatedly raised concerns with city officials regarding the handling of complaints and overall accountability, but in her view, mayors, police chiefs and city councils have come and gone without uprooting the underlying causes.
"Because we have so failed to address police conduct in this community, it made it literally inevitable that somebody was going to die this way," Gross said.
Concerns over the city's handling of police discipline have led to a long history of intervention.
In 2003, the police department entered a mediation agreement with the Department of Justice that sought to facilitate reform and address issues including use of force and race relations.
In 2007, five black Minneapolis police officers, including the department's current chief, Madaria Arradondo, filed a civil lawsuit that alleged African American officers in the city were disciplined "more harshly and frequently than...white officers for comparable or more serious misconduct." The suit was settled out of court for over $800,000, according to an attorney for the officers.
In 2015, a Department of Justice analysis requested by Minneapolis police found that "serious disciplinary actions against officers occur infrequently." The review did state that the police department consistently used proactive interventions like "coaching" in response to complaints but recommended the department improve its system for identifying and correcting problematic officers.
In 2016, a local police oversight commission detailed "several issues" with the complaint-filing process. The committee used "testers" to try to file complaints against police officers at several precincts in the city, and found that in 13 of 15 attempts, "complainants were not offered the opportunity to file a complaint at the precinct," according to a draft report posted on the city's website.
R.T. Rybak, the mayor of Minneapolis from 2002 to 2014, said he tried for years to change the system, but, reflecting on the current state of affairs, admits he did not get the job done.
He told CNN he presided over four different police chiefs with four different reform agendas, fought for more transparency in complaints, pushed to keep police officers from living outside the city and sought to diversify the force.
"If I had an easy answer about why we haven't gotten more done with police reform in Minneapolis, we wouldn't be in this mess today," Rybak said.
Rybak said the department is in need of deep cultural change, and specifically that the contract between the police department and the police union needs an overhaul.
"I remember being in many discussions about wanting to take harder discipline and running into all sorts of contract issues," said Rybak, who added that the current contract has limited the ability of the city to implement reforms.
Michael White, a professor in the school of criminology and criminal justice at Arizona State University and a former deputy sheriff, said complaints, whether sustained or not, can be indicative of patterns in an officer's performance.
"The vast majority of complaints are not going to be sustained because there isn't corroborating evidence," said White, who called the 18 complaints against Chauvin a "red flag."
White noted that some portion of complaints against officers in any city will be frivolous, but that handling of complaints, frivolous or not, is "critically important" for establishing public trust.
Repeated complaints against officers
Derek Chauvin isn't the only officer criminally charged after the death of Floyd to have previously faced complaints.
Tou Thao, who stood by as Chauvin knelt on Floyd's neck, has had six complaints filed with against him. Five were closed with no discipline, according to the city's complaint database.
One of those complaints was filed by Lamar Ferguson, who sued Thao and another officer in 2017 for allegedly using "unreasonable force" in the form of "punches, kicks and knees to the face and body" during Ferguson's arrest in 2014. Ferguson's police complaint against Thao was dismissed with no discipline, but the city paid $25,000 to settle the suit. The city and the officers denied liability in the settlement.
Jenna Nelson, an ER nurse and Minneapolis resident, also filed a complaint against Thao.
She said in 2017, she called police after an assault. Thao responded to the incident, but when she explained what happened, she said Thao was dismissive and suggested she go to family court.
"I just felt like he didn't care and wasn't willing to do anything about why I called," Nelson told CNN.
Nelson said she later followed up with the police department and learned that Thao never filed a report about what happened. She submitted a complaint online, but she said eight months passed before she was interviewed by a city investigator about Thao. USA Today first reported her description of the complaint.
Her complaint against Thao remains open today. A lawyer for Thao declined to comment on the complaints against him.
Phillip Atiba Goff, co-founder and president of the Center for Policing Equity and a professor at John Jay College of Criminal Justice, said effectively responding to complaints against officers can help reduce misconduct, but he argues that focusing on complaints against "a few bad apples" misses the broader issue.
"The problem in policing is not the few who behaved outside of policy," Goff said. "It's the many who behave inside of policy, which means it's the policy that's the problem."