Filed 3-day, but tenant probably not there

[John D.]

Bought a property at foreclosure auction a month ago.  Supposedly occupied by the former owner.  Seems likely he's not living there and has just staged the place as such, and comes by once every other week to check on the place.  My property manager posted abandoned property notices which sat for 2 weeks before he noticed, and called and yelled about trespassing.

I am having a process server post a 3-day notice to pay rent or quit.  What happens next if I get no response, can i forcibly enter the place and gain control?  And if I do get a response, what response prompts what further action?