Police say Johnson remains hospitalized after being shot by officers responding to Wednesday's shooting. It's not clear if she has an attorney.
Police previously confirmed the suspect is a 44-year-old homeless woman under police guard at Illinois Masonic Hospital. She is reported to be in critical but stable condition.
A published report says, only days before the shootings at Belmont and Western, the 4-foot-11, 290-pound mentally ill suspect who grew up on the West Side had suffered seizures and had pulled a knife on one of her four daughters.
The woman allegedly caused a disturbance on board a CTA bus before dawn Wednesday. During a struggle with Officer Richard Francis, who had responded to a call for help, witnesses say she grabbed the patrolman's revolver and fired three shots, hitting Francis twice in the torso and once fatally in the head.
"We're reminded this week in Chicago, the sacrifices that are paid by the men and women who serve in law enforcement," said Sen. Richard Durbin, (D) Illinois.
Durbin paid tribute to Francis Thursday morning during a ceremony at the city's gold Star Memorial set up to honor Chicago police officers killed in the line of duty.
"The death of Richard Francis, a Chicago patrolman who died in the line of duty on Wednesday, is a reminder of the risk that all of these men and women in law enforcement take every day," Durbin said.
Francis was a 27-year veteran and winner of 35 honorable mentions and one department commendation. The 60-year-old lived in Jefferson Park with his wife and special needs daughter and was only three years short of earning full retirement benefits.
Superintendent Jody Weis, who visited the dead cop's family Wednesday, has been unavailable to respond to questions on why Francis was on patrol alone at 2 a.m. Former Superintendent Phil Cline, who now heads the Chicago Police Memorial Foundation, said while the department tries to avoid such assignments, they are allowed if the officer agrees to go it alone.
"It would be great to have all two-man cars during the nighttime hours, because it is the most dangerous time," Cline said.
It was announced Thursday that a wake will be held for Officer Francis from noon to 9 p.m. on Sunday at the Cooney Funeral Home on West Irving Park. The funeral will be 11 a.m. Monday at St. Monica Church on North Nottingham.
In lieu of flowers, the family requests that donations be made to the Chicago Police Memorial Foundation.
The Associated Press contributed to this report.