MINNEAPOLIS (AP) -- A Minnesota prosecutor says he doesn't yet have enough evidence to charge a Minneapolis police officer who killed an unarmed 911 caller this summer, blaming investigators who "haven't done their job.''

Officer Mohamed Noor shot Justine Ruszczyk Damond in July when she approached his squad car after calling 911 to report a possible sexual assault.

Hennepin County Attorney Mike Freeman is weighing whether to charge Noor.

Freeman was captured on video expressing his frustration at a holiday reception Wednesday night after he was asked why he hasn't announced charges.

Freeman's office has declined to comment.

A spokeswoman for the Bureau of Criminal Apprehension, which is leading the investigation, also declined to comment. Noor has refused to talk to the agency.