Moscow Police Don't Have Any Suspects

Evidence indicates that this was a targeted attack but the police chief James Fry kept saying and Moscow police have maintained this up to this point that they don't have any suspects so how do they know this. The coroner completed autopsies on all four victims she says she didn't find any indication of sexual assault and some of the victims had bruises and defensive wounds likely inflicted by a larger knife now police are looking for a military style Rambo style k-bar type combat knife.