Minneapolis (CNN) Justine Ruszczyk, the woman killed by Minneapolis police on Saturday, made two 911 calls that night to report a possible sexual assault near her home, according to transcripts released by the city Wednesday.

"I can hear someone out the back and I, I'm not sure if she's having sex or being raped," Ruszczyk said in the first call.

"... And I think she just yelled out 'help,' but it's difficult. The sound has been going on for a while, but I think, I don't think she's enjoying it," Ruszczyk said.

Justine Ruszczyk, 40, was killed one month before her wedding.

The dispatcher told her police would be there soon.

Eight minutes later, Ruszczyk called 911 again, saying officers had not arrived. The dispatcher told her police were on the way.

That was 11:35 p.m. Moments later, police arrived, and an officer shot Ruszczyk. She was pronounced dead at 11:51 p.m.

Officer gives explanation

After days with no answers, authorities have offered the first clues about what may have led police to shoot Ruszczyk.

Two officers came to investigate her 911 report: Matthew Harrity and Mohamed Noor.

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As they drove down the alley in their police car, Harrity heard a loud sound that startled him, the officer told state investigators.

That's when Ruszczyk approached Harrity's driver's side window. Noor, sitting in the passenger seat, fired his gun and shot Ruszczyk through the driver's side window, Harrity told investigators.

The newly released explanation came after Harrity spoke with the Minnesota Bureau of Criminal Apprehension, or BCA, which is leading the investigation.

Noor won't speak to investigators. But radio traffic from the officers tell more of the story.

Audio: Officers scrambled to save woman's life

Immediately after Ruszczyk was shot, both officers got out of the car and tried to help save her, Harrity told investigators.

Dispatch audio from the officers captured the anxiety as they waited for an ambulance to arrive.

"(Squad) 530, uh, shots fired," one of the officers says. "Can we get EMS code 3, Washburn and 51st Street? We've got one down."

The dispatcher then calls for other units, and an officer -- it's not clear which -- says someone is starting CPR.

An officer tells other units they are in the entrance of an alleyway between houses.

The dispatcher asks the officer on the radio whether the situation is under control, and whether the ambulance can safely approach the shooting scene.

The officer says it's safe. "There are no suspects at large," he says.

Later, an officer's voice gets increasingly tense while waiting for the ambulance.

"Where is EMS on this?" he says.

The audio was provided to CNN by the operator of Minnesota PoliceClips, a company that monitors and records police radio dispatches.

Neither police nor the city of Minneapolis communications department would verify the authenticity of the Minnesota PoliceClips recording. But Assistant Police Chief Medaria Arradondo confirmed that, after canvassing the area, the officers found no evidence of sexual assault.

Roadblocks in the case

For days, Ruszczyk's family and the mayor of Minneapolis have expressed growing frustration about the slow trickle of information from the Bureau of Criminal Apprehension.

But some of the documents in the case have been shared with Ruszczyk's family, City Council member Linea Palmisano said.

Noor, however, won't be releasing details anytime soon. The officer who shot Ruszczyk has exercised his constitutional right to not speak to state investigators, the BCA said Tuesday.

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Mayor Betsy Hodges urged Noor to make a statement on the case.

"He has a story to tell that no one else can tell," she said. "We can't compel him by law, but I wish that he would make that statement."

Investigators also want to talk to a man on a bicycle who watched police perform CPR on Ruszczyk, and are asking him to come forward.

The case also is hampered by the lack of video footage. The police car's dashcam was not turned on, and neither of the officers' body cameras were on at the time, officials said.

It could take two to four months before the BCA finishes its investigation, said Chuck Laszewski, a spokesman for the Hennepin County attorney's office.

Once that happens, Hennepin County attorney Mike Freeman -- not a grand jury -- will decide whether either of the two officers involved should be charged in Ruszczyk's death.

Body camera policy reviewed

Minneapolis police policy says body cameras should be turned on prior to use of force "as soon as it is safe to do so" and during "any contact involving criminal activity."

The department is in the process of rolling out body cameras to all units and officers, and an updated policy is forthcoming, Arradondo said.

The department was eight months away from a full department-wide rollout, he said. By next month, mandated supervisor training will be completed throughout the department, and front-line supervisors must ensure officers increase the use of their body cameras, he said.

Meanwhile, the department has opened an internal affairs reivew on use of force, he said. But it's on hold as the BCA has custody of evidence for its investigation.

The mayor lamented the lack of body camera footage, but called for patience as the investigation continues.

"Body cameras are a very powerful tool, not an infallible tool, but a powerful one that have proven useful in our investigations," she said.

"The information the BCA has shared today gets us closer to having answers, closer to seeing justice done. And we do have more information now, though it's frustrating to have some of the picture, but not all of it."

Grief around the world

Ruszczyk, 40, was originally from Australia but moved to the United States in 2014. She trained as a veterinarian and later became a yoga instructor and life coach.

She was living with her fiancé, Don Damond. They were planning to marry next month.

Don Damond, middle, mourns the loss of his fiancee, Justine Ruszczyk.

"It is difficult to fathom how to go forward without her in my life," Damond said Monday. "Our hearts are broken, and we are utterly devastated by the loss of Justine."

"It is inexplicable. Our hearts go out to her family," Turnbull told Australian Channel 9's "Today" show Wednesday.

"I mean, how can a woman out in the street in her pajamas seeking assistance from the police be shot like that? It is a shocking killing."

Ruszczyk's father made an emotional plea for justice.

"Justine, our daughter, was so special to us and to so many others," John Ruszczyk told journalists in Australia. "Justine was a beacon to all of us. We only ask that the light of justice shine down on the circumstances of her death."