MINNEAPOLIS — A Minnesota prosecutor said he doesn't yet have enough evidence to charge a Minneapolis police officer who killed an unarmed Australian woman this summer, blaming investigators who "haven't done their job."

Hennepin County Attorney Mike Freeman is still deciding whether to charge Officer Mohamed Noor, who shot Justine Ruszczyk Damond in the alley behind her home in July. Damond had called 911 to report a possible sexual assault. As she approached the squad car, Noor fired from the passenger seat, across his partner and through the driver's window.

Damond's death sparked protests and led to a police department shake-up, including the resignation of Chief Janee Harteau.

Freeman was captured on video expressing his frustration at a Minneapolis Regional Labor Federation holiday reception Wednesday night, after he was asked about a charging decision. Union member Sam Sanchez recorded the conversation and posted it on Facebook. It wasn't clear if Freeman knew he was being recorded.

In the video, Freeman said he doesn't have enough evidence yet to decide whether to charge Noor, who has declined to speak with investigators.

"I've got to have the evidence. And I don't have it yet. And let me just say, it's not my fault," Freeman said. "So if it isn't my fault, who didn't do their jobs? Investigators, and they don't work for me. And they haven't done their job."

Freeman didn't name the investigators or their agency, but the state Bureau of Criminal Apprehension is leading the investigation. The BCA turned the case over to Freeman in September. The bureau issued a statement Thursday saying it continues to work with Freeman's office.

"The BCA conducts the majority of officer-involved shooting investigations in Minnesota, and the collaboration between prosecutors and investigators as a case file is reviewed under the statutes is a typical part of the review process," the BCA statement said. "State law prohibits us from providing additional details, because it is an active investigation."

Freeman had previously said he expected to make a charging decision by the end of the year. His office acknowledged the video Thursday and did not dispute its authenticity.

"We are working diligently on the case to complete the investigation as soon as possible," the statement said. "Beyond that, we cannot comment at this time."

Freeman indicated that Noor's refusal to speak had put prosecutors in a difficult position.

"I have to prove beyond a reasonable doubt, (that) the moment he shot the gun, he feared for his life. And he used force because he thought he was gonna be killed," Freeman said. "But I can't. He won't answer my questions because he doesn't have to, OK? We all have Fifth Amendment rights, and I respect that. So I can't talk to her because she's gone, and the other cop just gave us some (expletive), OK? So guess what? I gotta figure out angles of the shot, gun residues, reckless use of force experts."

Freeman didn't immediately respond to a request from The Associated Press for an interview. In an email to the Star Tribune, Freeman declined to respond to questions about how investigators have failed to do their job.

"Good questions and I respect you asking them," Freeman wrote in the email. "We are working very hard to complete our review of the facts provided in the investigation to date and to assist in helping to complete the investigation."

Sanchez is also an organizer with the Twin Cities Coalition for Justice 4 Jamar, which was formed after fatal shooting of Jamar Clark by a Minneapolis police officer in 2015. Freeman decided not to charge the officers involved in that case.

Minneapolis attorney Bob Bennett, who represents Damond's relatives in Australia, told MPR he was concerned but not surprised by Freeman's comments

"I hope that the BCA hasn't so irretrievably damaged the evidence, or failed to recover evidence that should be reasonably expected to be recovered at the time that the crime occurred," Bennett said. "And I use the term crime pointedly and intentionally."

Noor's attorney, Thomas Plunkett, said he was concerned by Freeman's remark that having enough evidence to make a charging decision would be "the big present I'd like to see under the Christmas tree." He also said the job of investigators is to gather evidence, not create it.

"No lawyer wants their client placed under a Christmas tree as a present to a vocal segment of the community. That said, this case is about an officer that follows procedure and training," Plunkett said. "This led to the death of a very fine person which is a horrible tragedy, but not a crime."