Not sure how long tenants can live for free after you've filed for eviction in Pittsburgh but I've heard that up North particularly in the winter it can be a long time. I know in Georgia the quickest eviction I ever had was when I got a call from SWAT at 2am letting me know they were boarding my place up after coming in through the windows and doors to remove the tenant who it turns out was into all sorts of illegal activities. I had already filed eviction due to non-payment of rent.
We were out there the next day and we were able to get the unit turned and re-rented to some good people in less than a week. Saved me at least two months. I'd definitely let the cops know. They'll either do something with the info or not. Can't hurt. In conjunction with everything Ralph S said of course.
