(CBS) — The family of a mentally ill woman gunned down by Chicago police officers last month say it didn’t have to happen.

CBS 2’s Roseanne Tellez says they are calling for better police training.

Police responded Feb. 10 to reports of a woman with a knife threatening employees at a CVS pharmacy in the North Center neighborhood. They say they confronted the woman at a bus stop at Western Avenue and Irving Park Road and she lunged at them with the weapon. When a Taser failed to subdue her, officers say they were forced to shoot.

Watching reports about the incident television, Dorothy Robey would later learn it was her 55-year-old daughter, Michelle.

“That was my daughter, who, without proper intervention, was just gunned down — I mean, shot in the stomach,” Robey tells Tellez.

Michelle was a mother, with a master’s degree in psychology. She had worked in medical research. Her family says she first showed signs of mental illness in 2009. Her most recent diagnosis: bipolar schizoaffective disorder.

“She was brilliant, she was compassionate,” says Stacey Robey, Michelle’s sister. “She never asked for mental illness.”

Michelle had had three previous encounters with police in January, was sent to the hospital, and each time released.

“Evaluate, medicate and evacuate — that’s what medical people call it,” Dorothy Robey says. “And she was evacuated out onto the street in a perilous condition.”

The family now plans to file suit. Attorney Michael Oppenheimer says Michelle’s civil rights were violated.

“Why didn’t they call a crisis intervention team? Why didn’t they call someone who is qualified to deal with mentally ill people to deal with this?” the attorney says. “This absolutely did not have to happen.”

The family says their goal is to make sure police are better trained to deal with mental illness so no other families have to go through this.

The Independent Police Review Authority is investigating. The officers involved in the shooting are still on desk duty, pending the investigation.