By Eric Levenson and Carma Hassan

CNN

(CNN) -- Minneapolis police officers will soon be required to activate their body cameras in an expanded set of situations, a change that comes in response to the fatal -- and unfilmed -- police shooting of Justine Ruszczyk on July 15.

"What good is a camera if it's not being used when it may be needed the most," acting Minneapolis police chief Medaria Arradondo said on Wednesday in announcing the new rules.

In particular, the new policy directs officers to turn on body cameras upon being dispatched, when they start to travel to a call for service, and prior to any law enforcement action. Body cameras are specifically required to be activated prior to "any contact with a reporting person, victim, suspect or witness," according to a copy of the updated policy.

The updated body camera policy will go into place on Saturday, Arradondo said, two weeks to the day since Ruszczyk was fatally shot by a Minneapolis police officer in an alley behind her home.

Bob Kroll, president of the Police Officers Federation, released a statement calling the policy change "a knee-jerk reaction and politically motivated."

"Changes need to be carefully examined and made collectively by the administration and the federation," according to Kroll's statement.

The shooting of Ruszczyk, details of which remain remarkably unclear, has caused outrage in the United States and in her native Australia and led to the resignation of the Minneapolis Police chief over the weekend.

No video of shooting

Ruszczyk, a 40-year-old bride-to-be, had called 911 late that Saturday night to report a possible sexual assault, and two police officers soon arrived to the scene. Less than 30 minutes later, she was dead from a gunshot wound to the abdomen.

Body cameras must be manually activated by officers, but the officers did not turn on their body cameras before the shooting. The squad car camera also did not capture the shooting, investigators said.

That lack of video evidence has frustrated city officials, including Minneapolis Mayor Betsy Hodges.

"Many of you have asked why the officers' body cameras weren't activated, and I'm asking the same question," Mayor Hodges said in a statement last week. "Right now, we don't know."

Officer Matthew Harrity told investigators that he drove to the scene and was startled by a "loud sound" near the squad car, according to Minnesota's Bureau of Criminal Apprehension. Immediately after, Ruszczyk approached the driver's side window, and Harrity's partner, Mohamed Noor, shot Ruszczyk through the window, Harrity said.

A search warrant from Hennepin County District Court obtained by Minneapolis Public Radio suggests that startling sound may have been a slap of the patrol car from Ruszczyk.

Noor declined to be interviewed by investigators, and his attorney did not clarify when if ever he would give an interview. Investigators cannot compel him to give an interview.

Both Harrity and Noor are on administrative leave amid the investigation into the shooting.

Noor, the first Somali-American officer in his precinct, expressed condolences to Ruszczyk's family in a statement through his lawyer. "He takes these events very seriously because, for him, being a police officer is a calling," the statement said. "He joined the police force to serve the community and to protect the people he serves. Officer Noor is a caring person with a family he loves and he empathizes with the loss others are experiencing."

"This should not have happened," former police chief Janeé Harteau said. "On our squad cars, you will find the words: 'To protect with courage and serve with compassion.' This did not happen."

A need to regain community trust

The body cameras have been fully in use for about eight months, but Arradondo said that "it takes time to get used to it."

Arradondo said that supervisors have been trained on how to audit officers' body cameras to ensure they were being used properly. And he reemphasized that the failure to follow body camera protocol could lead to suspension or termination.

"Cameras help give everyone a clear picture of an event," Arradondo said.

Inspector Michael Kjos said they were in the process of equipping all squad cars with auto-activation, meaning that when the squad lights are activated, the technology will activate the body cameras. That process will take a couple of months, he said.

Still, he said body cameras are just a tool, and explained that the issues facing the Minneapolis Police were much larger.

"We need to build and regain our community's trust. That is my charge and I've expressed that to all of our officers," he said.

Arradondo said they provide their officers with lots of equipment, but "the one thing we cannot equip them with is the benefit of the doubt, and they have to gain that through the relationships with the community."

In a statement, Minneapolis Mayor Betsy Hodges said the changes were a "step in the right direction" and have been in the works for some time.

The ACLU of Minnesota said in a statement that it supports the policy updates. "We trust that the implementation of a more robust body camera policy, as well as stricter accountability measures for violating the policy, will lead to greater accountability and transparency," the group said.

CNN's Brad Parks contributed to this report.