There are cases where LE knows exactly who the suspect is and do not want to tip them off that they know. I would hope that is the case in this situation. If the suspect is tipped off they may be more likely to do something drastic.
I saw that it was a possible Bumble date... I wonder if they have tried or even if there is a way to hack into her Bumble account to see if they can determine who she may have been with.