Would just need to link the SA owner of the top floors to FBI or someone they contacted on their phones or burner phones.
It would take planning to assassinate a high level gov official with protection detail. And what they found in the garage and never revealed. The multiple shooters that witness died trying to tell about?
Remember the LV anon that said he knew the battery dude that killed himself and daughter with a shotgun 2 days after LV shooting?
Yes the VIP airstrip is withing sniper range from a different window.