(CBS News) CHICAGO - President Barack Obama is keeping up the pressure on Congress to pass new gun control legislation.
He met at the White House today with police officials from around the country, including: Aurora, Colo.; Oak Creek, Wisc.; and Newtown, Conn. - all the scenes of recent mass shootings.
The president called on Congress to pass an assault weapons ban.
In Chicago, gun violence is taking more and more lives: 50 since Newtown.
Among the seven people murdered in Chicago this past weekend was 33-year-old Ronnie Chambers, shot dead in a parked van.
He was the last surviving child of Shirley Chambers, who now has lost all four of her children to gun violence. CBS News spoke to her Monday at a local funeral home.
"It's not Chicago. It's these people. It's these people with these guns. They shouldn't have guns, you know?" Chambers said.
Her son was a former gang member who stole cars, sold drugs and spent time in prison.
"He had changed a lot. He was trying to help other people. So whatever he did in the past, that's in the past. He changed," Chambers said of her son.
Just last month he appeared on the Ricki Lake show as an example of transformation.
"I told myself that you know, I need to protect my mother and be out here for her," Ronnie said on the show.
Mayor Rahm Emanuel told CBS News the problem here is more than guns.
"I think we have to deal with this -- not just with our gun controls -- but with a values-based education," he said.
He made his frustration clear at the height of the violence last summer.
"It's not about crime. It's about values," Emanuel had said at a press conference. "Where were you raised and who raised you?"
In the interview with CBS News, Emanuel explained why that question resonated with a lot of people.
"There is a values piece where people are so, I don't know, careless, dismissive -- totally are devoid of any sense of right from wrong," he said.
Shirley Chambers insists her son was different.
"Ronnie knew right from wrong," she said. "He wanted to change his life for his mother. He loved me and I loved him."