I am in the Philly, PA area.Can I have her arrested for trespassing on day 61 (the day after the 60 day notice expires)?

I have some 3 days until the offer expires!

The tenant hasn't paid for 3.5 months and his lease expired on March 1, 2016.  

Agent only show you listed properties, you need to find unlisted or expired listings, I am a broker in Baltimore, I find agents to be for the most part non responsive to investor's needs.Most want the quick in and out deal, nothing too complicated, show me the commission thought is their primary motivation, most do not counsel, don't understand creative financing, delayed settlement, Control and Roll, or the many clauses to benefit investors, a skinny contract offer or what to exclude in their 35 page standard purchase contract.SORRY AGENTS, I have been in your culture for over 40 years, I live and understand it.I know this is a silly statement, but I'll make it anyhow; "If agents knew what we investor know about real estate and the money we make, thy wouldn't be agents representing others, they'd be their own best client."

I've worked with some expired listings, but I can't/won't get a deal on a MLS listed property.  

I was talking to a lady who said she had to keep checking they haven't expired and such.

Before my lease expired, I wanted to close on a good four-plex that brought in a good cash flow and that I could also live in (house hack).

Very possible they are not happy with the realtor or maybe even the listing expired.

It likely is similar to an IRS lien, whereby they would have a right of redemption, which expires 120 days after the foreclosure sale.  

Thus, the prior estate must be one that is capable of ending naturally, for example upon the expiration of a term of years or the death of a life tenant.