Rivera was killed in a friendly fire incident on June 5. She was shot by her partner, Officer Carlos Baker.
There is also new insight Thursday on the history of complaints against Officer Baker, uncovered by the ABC7 I-Team.
Lawyers shared more details surrounding the Cook County case Thursday. They said Rivera's death was completely preventable and should never have happened.
READ MORE | Cop tied to CPD Ofc. Rivera's death accused of trying to gather video evidence of alleged bar attack
ABC7 Chicago obtained Rivera's autopsy records, which showed she was shot from behind.
Police say Rivera's partner accidentally shot her, as they were chasing a suspect in Chatham.
Attorneys on Thursday alleged Rivera and Baker were previously in a relationship before the shooting, and Rivera had recently requested a new partner after the two broke up.
New details in lawsuit filed in friendly fire shooting of Ofc. Rivera
The lawsuit claims Baker had an adverse and hostile reaction to her choice to end a two-year on-and-off romantic relationship between the two of them.
Court documents also show the breakup stemmed from Baker's relationship with another woman, adding that Rivera had threatened to tell Baker's girlfriend, who was living with him at the time, about their relationship.
Attorneys also said Rivera told CPD Baker was "reckless" and requested a transfer or partner reassignment.
Wrongful death lawsuit filed in friendly fire shooting of Ofc. Rivera
According to the lawsuit, Baker showed up uninvited to Rivera's home just one day before the two of them chased a gunman into a Chatham apartment back in June, where they ran into a second armed man.
During a press conference Thursday, lawyers said Baker did not help Rivera after she was shot, and Rivera radioed in her own shooting.
"Baker made intentional decisions not to come to Rivera's aid," lawyers said.
Wrongful death lawsuit announced in CPD officer shooting
The suit says specifically he failed to provide medical aid, call for an ambulance or acknowledge that he was the shooter.
Baker has not been charged in her death.
Yolanda Rivera, Officer Rivera's mother, filed the lawsuit against the Chicago Police Department and Baker.
Rivera's mother and other close family members joined attorney Antonio Romanucci to open up about the lawsuit Thursday.
"Baker left Krystal there on the floor literally gasping," Romanucci said. "Krystal radioed in her own shooting."
Baker has since been relieved of his police powers amid a separate assault investigation, CPD said.
He's accused of punching a female off-duty officer. But he claims that he was the victim in the alleged assault outside a Wicker Park bar.
Earlier this year, the ABC7 Chicago I-Team reported on a 2024 Civilian Office of Police Accountability disciplinary report, which uncovered that Baker had five previous complaints of misconduct, where findings were sustained. He also faced three suspensions and two reprimands in just four years with the department.
When asked, CPD did not respond to COPA's disciplinary findings, but ABC7 police affairs consultant Bill Kushner, a former academy instructor, says it's obvious warning signs were missed.
"If you look at his record of conduct from 2022 to 2025 somebody dropped the ball big-time with this kid, with this officer. He should not have been in the street. He should probably not have been on the job," Kushner said.
Baker's attorney Timothy Grace shared the following statement with the ABC7 I-Team Thursday evening:
"Officer Carlos Baker and his partner Officer Krystal Rivera were confronted with a dangerous and life- threatening situation on the date of the incident.
'Like many of our officers do on a daily basis, they attempted to apprehend dangerous gun wielding individual from the streets of Chicago.
"The effort of Carlos and Krystal to make our city safer resulted in the tragic loss of Krystal's life.
"Officer Baker shares with Krystal's family the overwhelming grief that has accompanied her death.
"However, the cold hard truth is that the reason this City has lost one of its great officers is not due to the actions of Officer Baker but rather the fact that a person decided to flee from Chicago Police Officers with a loaded handgun equipped with a drum magazine and another who decided to point a riffle at those same officers.
"The heartache and grief that has afflicted the Chicago Police family which includes Krystal's family members and loved ones is unfathomable.
"There is nothing more painful and devastating for a Chicago Police Officer than to experience the death of their partner in the line of duty. A lawsuit has been filed and the pain is understandable but unfortunately misdirected.
"The facts are clear that Officer Baker breached the door on that fateful night and was facing the lethal end of a rifle.
"While moving to seek cover and unbeknownst to him, his weapon unintentionally discharged striking Krystal.
"The height of both officers, their location, the angle of the service weapon and the exact positioning of both officers created a unique, dynamic and deadly circumstance that could not be duplicated in a controlled environment not to mention the actual situation they were confronted with.
"The true facts will reveal, that Carlos immediately called for EMS, carried Krystal to safety, and ensured she was being transported to the hospital.
"He then reentered the apartment to apprehend the offenders.
"The body worn camera videos will support these facts and challenge the accuracy and veracity of the allegations made in the complaint.
"Officer Baker will not be intimidated and will defend his actions that night.
"This is a tragic moment in the history of the Chicago Police Department and I would urge caution to all of the amateur armchair tactical experts until all the evidence has been released."