When a rising number of victims are found brutally murdered one by one at a remote Veteran Hospital off the main land, a rookie detective and her seasoned partner must race against time to find the killer but not everyone is who they appear to be.

I believe the idea itself is solid, (Although I am not sure if this would be police jurisdiction or FBI, that could be an issue)

I would personalize it.
One of the victims should be someone the lead character knows such as her brother or someone she served with in combat.
That one specific death should be the inciting incident and that will shorten your set-up.
Because that is the current problem with your logline, there is a lot of set up, which doesn't leave a lot of room to inform us about story.