If an algorithm can accurately predict who Chicago’s violent gun offenders are, then why are they allowed to shoot up the city?

That’s a question Police Supt. Eddie Johnson faced Monday afternoon during a question and answer session following an address to the City Club of Chicago, a nonpartisan group that hosts forums and debates, at Maggiano’s restaurant.

The answer seems to be common sense, but frustrating none the less after a weekend when more than a dozen people were fatally shot in the city.

“They still have to commit a crime,” Johnson said. “We still have to be mindful of people’s civil rights.”

The city knows the identities of the approximately 1,400 people who are committing the violence, but the best police officers can do is remain vigilant, Johnson said.

“The CPD can’t just go pluck them off the street until they actually do something that we can arrest them for,” he said.

Johnson said that police take a pro-active approach by knocking on their doors and attempting to guide people on the list — often gang members — to services to help change their lives.

Johnson also summed up the challenges officers face with a sobering statistic: Since the beginning of the year, police had removed one illegal gun per hour from the street — more than police departments in Los Angeles and New York combined.

Johnson also said his goal of restoring public trust in the police department is well underway.

“I am optimistic about the gains we’ve made in terms of restoring trust,” Johnson said.

“I am seeing progress and a lot of that is because we are engaging in town hall meetings with different parts of the city,” he said, noting that he had attended about 30 such gatherings.

“The one thing I always hear people say, without question, is that it’s not that they don’t want the police in their communities, they just want the police in their communities to be professional, respectful and treat them fair,” he said.

“So in order to resolve a lot of the gun violence we have in the city, my challenge with CPD internally is to get us to that point and we are making strides to get there,” he added.

Johnson said the police department is adjusting to recommendations from a task force Mayor Rahm Emanuel formed to dissect problems within the department.

“I think they gave us 76 recommendations,” Johnson said. “Within four days we had implemented a third of them, so that shows you that we are serious about change in CPD internally. Because unless the public believes that we are serious about this change, they’ll never give us the trust that we need.

He noted that the police are “only as effective as the trust the community has in it.”

“The majority of the men and women in blue do want to do the right things, they want to treat the communities respectfully and fairly, sometimes they get a little bit off track, and it’s our job to identify inappropriate behavior early on so we can get that police officer back on track,” Johnson said. “Now we have a small sub-section that I believe is engaged in inappropriate activity and there is zero tolerance within CPD for that kind of activity.”

During a post-luncheon chat with reporters, Johnson was asked about allegations of excessive force used by an officer caught on video stomping the head of a suspect who was resisting arrest. He defended the officer.

“His partner was being attacked, and he helped resolve that issue,” Johnson said. “Sometimes the day-to-day things that police do, it’s not going to look pretty all the time. It’s not. But my challenge is to make sure we’re doing it properly, and that when they get off track to get them the right training, counseling, mentoring and coaching and get them right back on the street.”

“Being a police officer is not easy. We’re asking these guys to make split-second decisions and rely on their training,” he said.

Johnson shared the stage with Kim Foxx, Democratic nominee for Cook County state’s attorney, the Rev. Michael Pfleger, and Cleopatra Pendleton, the mother of slain teenager Hadiya Pendleton.

The Rev. Michael Pfleger, pastor of St. Sabina and an anti-violence activist, backed Johnson wholeheartedly.

“I love this man here and have total confidence in him,” said Pfleger, who stressed a need for more resources for poor areas of the South and West Sides. “Too many of our children are becoming road kill on the streets of Chicago.”

Kim Foxx, Democratic nominee for Cook County state’s attorney, also spoke on violence at the luncheon.

“Chicago is gripped in a crisis as it relates to homicides in our city,” she said. “We’re outpacing other cities of similar sizes.”

Foxx emphasized the need to look at broader issues that cause gun violence and invest in programs that stem the problem.

“We have to deal with our educational systems, our public health systems, our mental health systems in partnership with the goal of prevention, because enforcement comes after the fact,” she said.

Cleopatra Pendleton, who lost her teenage daughter, Hadiya, to gun violence, also spoke about the pain she suffered and how it’s caused her to become an advocate to stop violence.

“I am a permanent fixture in the city of Chicago because I cannot dig up what’s buried on 127th Street and carry it with me whereever I should go,” she said.